How to add thumbnail images to all posts within a category on the homepage?

To add the thumbnails for each post, please follow the steps here:
1) Open up the dw-focus-categories.php file in themes/dw-focus/widgets folder, find the code below (around line 290):

<li><h2 class="entry-title"><a href="<?php the_permalink(); ?>" title="<?php echo esc_attr( sprintf( __( 'Permalink to %s', 'dw_focus' ), the_title_attribute( 'echo=0' ) ) ); ?>" rel="bookmark"><?php the_title(); ?></a></h2></li>

.. and change it into this:

<li>
 <?php if( has_post_thumbnail( get_the_ID() ) ) { ?>
 <div class="entry-thumbnail">
 <a href="<?php the_permalink(); ?>" title="<?php echo esc_attr( sprintf( __( 'Permalink to %s', 'dw_focus' ), the_title_attribute( 'echo=0' ) ) ); ?>" rel="bookmark"><?php the_post_thumbnail(array(50,50)); ?></a>
 </div>
 <?php } ?>
 <h2 class="entry-title"><a href="<?php the_permalink(); ?>" title="<?php echo esc_attr( sprintf( __( 'Permalink to %s', 'dw_focus' ), the_title_attribute( 'echo=0' ) ) ); ?>" rel="bookmark"><?php the_title(); ?></a></h2>
 </li>

2) Go to Dashboard / Appearance / Customize / General Setting, and add the following code to the Header Code section:

<style>
.widget.news-category .other-entry li {clear:both;}
.other-entry .entry-thumbnail {float: left;}
.widget.news-category .other-entry h2 {margin-left: 60px;}
</style>

Hope this helps!

@jgitta ! At the moment, in the latest version still does not yet  support this issue.
@mohammed ! 
You can open the dw-focus-categories.php file. Find the line 442 & line 318 then Replace with the following code:

<li>
 <?php if( has_post_thumbnail( get_the_ID() ) ) { ?>
 <div class="entry-thumbnail">
 <a href="<?php the_permalink(); ?>" title="<?php echo esc_attr( sprintf( __( 'Permalink to %s', 'dw_focus' ), the_title_attribute( 'echo=0' ) ) ); ?>" rel="bookmark"><?php the_post_thumbnail(array(50,50)); ?></a>
 </div>
 <?php } ?>
 <h2 class="entry-title"><a href="<?php the_permalink(); ?>" title="<?php echo esc_attr( sprintf( __( 'Permalink to %s', 'dw_focus' ), the_title_attribute( 'echo=0' ) ) ); ?>" rel="bookmark"><?php the_title(); ?></a></h2>
 </li>

Then add the following code to the style.css file:

.widget.news-category .other-entry li {clear:both;}
.other-entry .entry-thumbnail {float: left !important;}
.widget.news-category .other-entry h2 {margin-left: 60px;}

Hope this helps !