Prevent Contributor to show comment list

Paste this code inside the functions.php file of your currently active theme. You can make it a plugin file too. It uses the “the_comments” filter to remove the unwanted comments from the backend table.

/**
 * Filter out comments of other posts than current logged-in user.
 *
 * @param $all_comments all the comments to be displayed in List_Table
 *
 * @return mixed filtered out comments.
 */
function filter_comments_by_contributor( $all_comments ) {
    // get the current logged in user
    $current_user = wp_get_current_user();

    if ( 0 == $current_user->ID ) {
        // Not logged in.
        return $all_comments;
    } else {
        // Logged in.

        // check if the logged-in user is a contributor
        if ( in_array( 'contributor', (array) $current_user->roles ) ) {

            // check if the user is on wp-admin backend,
            $screen = get_current_screen();
            if ( ! empty( $screen ) && 'edit-comments' == $screen->id ) {

                // get all posts by that contributor
                $args              = array(
                    'author'         => $current_user->ID,
                    'posts_per_page' => - 1,
                    'fields'         => 'ids'
                );
                $contributor_posts = get_posts( $args );

                // unset the comments given on posts other than his/her.
                foreach ( $all_comments as $key => $value ) {
                    if ( ! in_array( $value->comment_post_ID, $contributor_posts ) ) {
                        unset( $all_comments[ $key ] );
                    }
                }
            }

            return $all_comments;
        } else {
            return $all_comments;
        }
    }
}
add_filter( 'the_comments', 'filter_comment_by_contributor' );