form.scss

.wpforms-container#wpforms-57 {

	.wpforms-field-container {
		@include make-row;

		.wpforms-field-container-left,
		.wpforms-field-container-right {
			@include make-sm-column( 12 );
			@include make-md-column( 6 );
		}
	}
}

functions.php

<?php

/**
 * Contact Form Two Column open
 *
 */
function ea_contact_form_two_column_open( $field, $form_data ) {

	if( 57 != $form_data[ 'id' ] )
		return;

	if( 1 == $field[ 'id' ] )
		echo '<div class="wpforms-field-container-left">';

	if( 6 == $field[ 'id' ] )
		echo '</div><div class="wpforms-field-container-right">';
}
add_action( 'wpforms_display_field_before', 'ea_contact_form_two_column_open', 1, 2 );

/**
 * Contact Form Two Column Close
 *
 */
function ea_contact_form_two_column_close( $field, $form_data ) {

	if( 57 != $form_data[ 'id' ] )
		return;

	if( 6 == $field[ 'id' ] )
		echo '</div>';
}
add_action( 'wpforms_display_field_after', 'ea_contact_form_two_column_close', 99, 2 );