Pick stories to appear in DW Focus: News Slider

Sorry about that I have confused with another question, I will remove previous answer, please see the following solution:
Open the dw-focus-slider.php file in the folder path “yourdomain/wp-content/themes/dw-focus/inc/widgets/dw-focus-slider.php”. Then do as the following:
Step 1: Add Tag dropdown in Slider widget backend:
Find line 218 :

<p><label for="<?php echo $this->get_field_id('category'); ?>"><?php _e('Category:','dw_focus'); ?></label><br>
 <?php wp_dropdown_categories(array(
 'show_option_all' => 'All categories',
 'hide_empty' => 0,
 'id' => $this->get_field_id('category'),
 'name' => $this->get_field_name('category'),
 'selected' => $category,
 'class' => 'widefat',
 'hierarchical' => true,
 'walker' => new DW_Walker_CategoryDropdown()
 ) ); ?>
 </p>

Add some code after that :

<p><label for="<?php echo $this->get_field_id('post_tag'); ?>"><?php _e('Tag:','dw_focus'); ?></label><br>
 <?php wp_dropdown_categories(array(
 'show_option_all' => 'All tags',
 'hide_empty' => 0,
 'id' => $this->get_field_id('post_tag'),
 'name' => $this->get_field_name('post_tag'),
 'selected' => $post_tag,
 'class' => 'widefat',
 'hierarchical' => true,
 'taxonomy' => 'post_tag',
 'walker' => new DW_Walker_CategoryDropdown()
 ) ); ?>
 </p>

Step2: Add instance post_tag :
Find line 173 :
$instance[‘category’] = (int) $new_instance[‘category’];
Add:
$instance[‘post_tag’] = (int) $new_instance[‘post_tag’];
After that: 
Find line 194 :
$category = isset($instance[‘category’]) ? absint($instance[‘category’]) : 0;
Add:
$post_tag = isset($instance[‘category’]) ? absint($instance[‘post_tag’]) : 0;
After that.
Step 3 : Change WP_query
Find line 40 – 48 :

$r = new WP_Query( apply_filters( 'widget_posts_args', 
 array( 
 'posts_per_page' => $number, 
 'no_found_rows' => true, 
 'post_status' => 'publish', 
 'ignore_sticky_posts' => true,
 'cat' => $instance['category'],
 'meta_query' => array(array('key' => '_thumbnail_id')) 
 ) ) );

Replace that code with :

$r = new WP_Query( apply_filters( 'widget_posts_args', 
 array( 
 'tax_query' => array(
 'relation' => 'OR',
 array(
 'taxonomy' => 'category',
 'field' => 'id',
 'terms' => array( $instance['category'] ),
 ),
 array(
 'taxonomy' => 'post_tag',
 'field' => 'id',
 'terms' => array( $instance['post_tag'] ),
 ),
 ),
 'posts_per_page' => $number, 
 'no_found_rows' => true, 
 'post_status' => 'publish', 
 'ignore_sticky_posts' => true,
 'meta_query' => array(array('key' => '_thumbnail_id')) 
 ) ) );

Hope this helps !