This code snippet pulls posts from three different categories and sets them up as tabs.

tab-styles

/* Basic styles for tabs and tabbed content. */

/* Tabs */
.tab {
    list-style-type: none;
    margin: 0;
    padding: 0;
	width: 100%;
	
}
.tab li {
   	float: left;
    margin: 0;
}
.tab li a {
	display: block;
	color: #000;
    font-size: 1em;
	padding: 5px 20px;
    margin: 0px;
	text-decoration: none;
}

.tab li.active {
	background-color: #000;
}
.tab li.active a {
	color: #fff;
}

.tab-container {
	display: none;
}
.tab-container.active {
	display:block;
}

.flex-video{
	position: relative;
	padding-top: emCalc(25px);
	padding-bottom: 67.5%;
	height: 0;
	margin-bottom: emCalc(16px);
	overflow: hidden;
}
.flex-video iframe,
.flex-video object,
.flex-video embed,
.flex-video video {
	position: absolute;
	top: 0;
	width: 100%;
	height: 100%;
}

/* left and right columns */
.tabcontent-left {
	float: left;
	padding-right: 2%%;
	width: 28%;
}
.tabcontent-right {
	float: left;
	width: 70%;
}

WordPress tabbed Content

<div id="tabbed-content">
	<?php
	/* Set up tabs at the top using your three categories.
	 * I've created three posts in News, Photos and Videos categories
	 * Both news and photos have featured images. 
	 * The videos have a custom field (video) with the youtube embed code. 
	 * 
	 */
				
	?>
	<ul class="tab">
	        <li><a class="tab-switch" data-tab-container="tab-news" href="#tab-news">NEWS</a></li>
		<li><a class="tab-switch" data-tab-container="tab-videos" href="#tab-videos">VIDEOS</a></li>
		<li><a class="tab-switch" data-tab-container="tab-photos" href="#tab-photos">PHOTOS</a></li>
	</ul>
				
	<?php
	/*
	* Next you want to create three separate loops for each category 
	*/
	?>
				
		<div id="#tab-news" class="tab-container tab-news active">
					
			<?php
				$news = get_posts( array(
				'numberposts' => 3,
				'category_name' => 'News'
			) );

			if ( $news ) :
				foreach( (array) $news as $post ) {
				setup_postdata( $post ); ?>
			
			<div class="post">
				<h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
				<div class="tabcontent-left">
					<?php if ( has_post_thumbnail() ) : ?> 
						<a href="<?php the_permalink(); ?>"><?php the_post_thumbnail( 'featured-image' ); ?></a>
					<?php endif; ?>
				</div>
   				<div class="tabcontent-right">
					<?php the_excerpt(); ?>
				</div>
			</div>
  						
			<?php }
			endif; 
			wp_reset_postdata(); ?>

		<p class="view-more"><a href="<?php echo esc_url( home_url() ); ?>/category/news/">View More &raquo;</a></p>
                </div>
				
               	<div id="#tab-videos" class="tab-container tab-videos">
					
			<?php
				$videos = get_posts( array(
				'numberposts' => 3,
				'category_name' => 'Videos'
			) );

			if ( $videos ) :
				foreach( (array) $videos as $post ) {
				setup_postdata( $post ); ?>
			
			<div class="post">
				<h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
				<div class="tabcontent-left flexvideo">
					<?php $key="video"; echo get_post_meta($post->ID, $key, true);?>
				</div>
   				<div class="tabcontent-right">
					<?php the_excerpt(); ?>
				</div>
			</div>
  						
			<?php }
			endif; 
			wp_reset_postdata(); ?>
				   

			<p class="view-more"><a href="<?php echo esc_url( home_url() ); ?>/category/videos/">View More &raquo;</a></p>
                </div>
				
                <div id="#tab-photos" class="tab-container tab-photos">
					
			<?php
				$photos = get_posts( array(
				'numberposts' => 3,
				'category_name' => 'Photos'
			) );

			if ( $photos ) :
				foreach( (array) $photos as $post ) {
				setup_postdata( $post ); ?>
			
			<div class="post">
				<h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
				<div class="tabcontent-left">
					<?php if ( has_post_thumbnail() ) : ?> 
						<a href="<?php the_permalink(); ?>"><?php the_post_thumbnail( 'featured-image' ); ?></a>
					<?php endif; ?>
				</div>
   				<div class="tabcontent-right">
					<?php the_excerpt(); ?>
				</div>
			</div>
  						
			<?php }
			endif; 
			wp_reset_postdata(); ?>
					

			<p class="view-more"><a href="<?php echo esc_url( home_url() ); ?>/category/photos/">View More &raquo;</a></p>
                </div>

	</div><!-- #tab-content -->
	
	<?php
	/* Js needed to make the tabs work. 
	 * You could put this into an external file and enqueue it. 
	 */
	?>		
	    <script>
	        jQuery(document).ready(function($){
	            $('#tabbed-content').on('click','.tab-switch',function(e){
	                e.preventDefault();
					$(this).parent().addClass('active').siblings().removeClass('active');
	                var tabContent = "." + $(this).attr('data-tab-container');
	                console.log(tabContent);
	                $('.tab-container').removeClass('active');
	                $('.tab-container' + tabContent).addClass('active');
	            });
	        });
	    </script>