/**
 * Manage Nav menu classes
 *
 * @param Array $classes        - Array of string classes
 * @param WP_Nav_Item $item     - Similar to a WP_Post with additoinal properties
 * @param Object $args          - Menu Arguments
 *
 * @return Array $classes
 */
function theme_nav_item_classes( $classes, $item, $args ) {

    global $post;

        if( is_singular( 'post' ) && has_category( 'news' ) ) {

            if( 'News' === $item->title ) {
                $classes[] = 'current-menu-item';
                $classes = array_unique( $classes );
            } else if( 'Blog' == $item->title ) {
                $classes = array_diff( $classes, array(
                    'current_page_parent',
                    'current-post-ancestor',
                    'current-menu-parent',
                    'current-post-parent',
                ) );
            }

        }


    return $classes;

}
add_filter( 'nav_menu_css_class', 'theme_nav_item_classes', 10, 3 );