use this code 
add_filter('wpseo_breadcrumb_single_link', 'filter_breadcrumbs_for_h1', 10, 2);
function filter_breadcrumbs_for_h1($link_output, $link) {
    if ( is_category()  ) {
    $link_output = preg_replace("/<span\s(.+?)>(.+?)<\/span>/is", "<span $1>Category: ''$2''</span>", $link_output);
    return $link_output;
    }
    else if ( is_tag()  ) {
        $link_output = preg_replace("/<span\s(.+?)>(.+?)<\/span>/is", "<span $1>Tag: ''$2''</span>", $link_output);
        return $link_output;
        }
    else  {
        $link_output = preg_replace("/<span\s(.+?)>(.+?)<\/span>/is", "<span $1>$2</span>", $link_output);
        return $link_output;
        }
}