how to display image from rss

Try using the_post_thumbnail WP function, inside your <li id="news-single"> markup definition:

        <li id="news-single">

            <a href="https://wordpress.stackexchange.com/questions/228220/<?php echo esc_url( $item->get_permalink() ); ?>" target="_blank" title="<?php printf( __( 'Posted %s', 'my-text-domain' ), $item->get_date('j F Y | g:i a') ); ?>">
            <?php echo esc_html( $item->get_title() ); ?>
            </a>

            <?php
            // This is the piece of code that you should add:
            // You first need to check if the post has a thumbnail assigned.
            if ( has_post_thumbnail() ) {
                the_post_thumbnail();
            } 
            ?>

        </li>

Hope it helps!