This is a skeleton to create a BP My Home (version 2.0) widget. You can use it in your plugin or in the functions.php file of your active theme.

bpmh-custom.php

<?php
/**
 * 1- Extending WP_Widget
 *
 * Make sure to prefix your class with BPMH_ 
 * and to add a classname prefixed by bpmh-
 *
 */
class BPMH_Widget_Custom extends WP_Widget {

	function __construct() {
		$widget_ops = array('classname' => 'bpmh-widget_custom', 'description' => __( 'Custom BPMH widget') );
		parent::__construct( false, _x( '(BPMH) Custom', 'widget name', 'bp-my-home' ), $widget_ops );
		
		/** 
		* Hooking bpmh_actions to save user settings
		*/
		add_action( 'bpmh_actions', array( $this, 'save_user_settings' ) );
	}
	
	function widget( $args, $instance ) {
		extract( $args );

		$title = apply_filters('widget_title', empty( $instance['title'] ) ? __( 'Example' ) : $instance['title'], $instance, $this->id_base);

		echo $before_widget;
		
		/** 
		* 2- Configure link
		* 
		* if you need your widget to have a configuration area,
		* this is the way you need to build your configure link
		*/
		$widget_hash = trailingslashit( base64_encode( get_class( $this ) ) );
		
		$config_link = trailingslashit( bp_my_home_get_user_settings_link() . 'widget' ) . $widget_hash;
		
		if ( $title )
			echo $before_title .'<span class="configure" ><a href="'.$config_link.'">'.__('Configure', 'bp-my-home') .'</a></span>' . $title . $after_title;
		
		if( !is_admin() && !is_network_admin() )
			$this->user_content( $instance );
			
		else
			echo '<p>' . __( 'Content is only available in user&#39;s page', 'bp-my-home' ) . '</p>';
		
		echo $after_widget;
	}

	function update( $new_instance, $old_instance ) {
		$instance = $old_instance;
		$instance['title'] = strip_tags($new_instance['title']);

		return $instance;
	}
	
	/**
	 * Let Admin customize the title of the widget
	 *
	 * @param array $instance 
	 * @return string html of the form
	 */
	function form( $instance ) {
		$instance = wp_parse_args( (array) $instance, array( 'title' => '' ) );
		$title = esc_attr( $instance['title'] );
	?>
		<p><label for="<?php echo $this->get_field_id('title'); ?>"><?php _e('Title:'); ?></label> <input class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" type="text" value="<?php echo $title; ?>" /></p>
<?php
	}
	
	/**
	 * We could have done this in the widget() function
	 * but as this is never loaded in widget administration
	 * it avoids to run some un-necessary function in this part
	 * to only do it in user's home page
	 *
	 * @param array $instance
	 * @uses  bp_loggedin_user_id() to get current user's id
	 * @uses  get_user_meta() to get previously stored user meta
	 * @uses  esc_html() to sanitize output
	 * @return string html private content for the user
	 */
	function user_content( $instance = array() ) {
		$user_id = bp_loggedin_user_id();
		
		$bpmh_example_text = get_user_meta( $user_id, 'bpmh_custom_settings', true );
		
		if( !empty( $bpmh_example_text ) )
			echo '<p>'. esc_html( $bpmh_example_text ).'</p>';
	}
	
	/**
	 * 3- Displays the user settings form
	 *
	 * On the click of the configure link, BP My Home will call this function
	 * to display the user settings form for your widget.
	 *
	 * @param array $args 
	 * @param array $instance 
	 * @uses  bp_loggedin_user_id() to get current user's id
	 * @uses  get_user_meta() to get previously stored user meta
	 * @uses  wp_nonce_field() for security check
	 * @return string html form for user settings
	 */
	function user_settings( $args, $instance ) {
		extract( $args );
		
		$user_id = bp_loggedin_user_id();
		$bpmh_custom_text = get_user_meta( $user_id, 'bpmh_custom_settings', true );
		
		$title = apply_filters('widget_title', empty( $instance['title'] ) ? __( 'Example' ) : $instance['title'], $instance, $this->id_base);
		
		echo $before_widget;

		if ( $title)
			echo $before_title . sprintf( __('Settings for %s', 'bp-my-home' ), $title ) . $after_title;
		?>
		<form action="" method="post" class="standard-form">
			<label for="custom-id"><?php _e( 'Insert a random text', 'bp-my-home' )?></label>
			<input type="text" name="_bpmh_custom[input]" value="<?php echo esc_attr( $bpmh_custom_text );?>" id="custom-id"/>
			<?php wp_nonce_field( 'bpmh_custom_options', '_wpnonce_widget_options_' . $this->id_base ); ?>
			<p><input type="submit" name="_bpmh_custom[save]" value="Save"></p>
		</form>
		<?php
			echo $after_widget;
	}
	
	/**
	 * 4- Saves the user settings
	 *
	 * This function is hooked to bpmh_actions
	 * it first checks we're on the widget's settings area
	 * then stores the user's data to finally safely redirect the user to it
	 *
	 * @uses  bp_my_home_current_is_widget_settings() to check we're on a single widget settings area
	 * @uses  bp_action_variable() to check it's the settings area of the current widget
	 * @uses  check_admin_referer() for security check
	 * @uses  bp_loggedin_user_id() to get current user's id
	 * @uses  get_user_meta() to get previously stored user meta
	 * @uses  update_user_meta() to save the user meta in db
	 * @uses  delete_user_meta() to eventually delete user's data
	 * @uses  bp_my_home_get_user_settings_link() to build the redirection link
	 * @uses  bp_core_add_message() to inform the user data were processed
	 * @uses  bp_core_redirect() to redirect user to the widget settings page and avoid refreshing the posted vars
	 * @return string html form for user settings
	 */
	function save_user_settings() {
		if( bp_my_home_current_is_widget_settings() && base64_decode( bp_action_variable( 1 ) ) == get_class( $this ) ) {
			
			if( empty( $_POST['_bpmh_custom']['save'] ) )
				return;
			
			check_admin_referer( 'bpmh_custom_options', '_wpnonce_widget_options_' . $this->id_base );
			
			$user_id = bp_loggedin_user_id();

			if( !empty( $_POST['_bpmh_custom']['input'] ) )
				update_user_meta( $user_id, 'bpmh_custom_settings', sanitize_text_field( $_POST['_bpmh_custom']['input'] ) );
			else
				delete_user_meta( $user_id, 'bpmh_custom_settings' );
				
			// let's finally redirect to avoid double posting
			$widget_hash = trailingslashit( base64_encode( get_class( $this ) ) );
			$redirect = trailingslashit( bp_my_home_get_user_settings_link() . 'widget' ) . $widget_hash;
			
			bp_core_add_message( __( 'Widget settings saved successfully', 'bp-my-home' ) );
			bp_core_redirect( $redirect );
		}
	}

}

/**
 * 5- Finally let's register the widget for BP My Home
 *
 * @since BP My Home 2.0
 */
function bpmh_custom_register_widget() {
	/** 
	* 5-2 then we hook to bpmh_widgets_init to make sure BP My Home is up and running! 
	*/
	add_action( 'bpmh_widgets_init', create_function('', 'return register_widget("BPMH_Widget_Custom");' ) );
}

/**
 * 5-1 We first hook to widgets_init
 */
add_action( 'widgets_init', 'bpmh_custom_register_widget' );

Thank you for all your time!