I Need to use Month , year in my all archives and pages of my wordpress site

Please put below code in your functions.php file. You will need to create custom field named ‘custom_post_name’ and set the custom field text to what you want to add to page title.

function alter_page_title(){
    global $post;
    $current_page_title = $post->post_title;
    /* Check if lower case version of current page title is = online exams. */
    if (strtolower($current_page_title) == "online exams"){
        /* If yes then get value of custom_post_name meta field and add that to beginning of title & return */
        $custom_title_to_append = get_post_meta($post->ID, custom_post_name, true);
        return $custom_title_to_append. " ".$current_page_title;
    } else {
        /* else return title as is */
        return $post->post_title;
    }
}
add_action('the_title', 'alter_page_title');