Need to change block title

I've got a menu block that's machine name is 'menu-peanuts' . I need the title of the menu block to be the page/node title for instance:
I've got a page called 'Info' . I need the title of the menu block to be 'Info' on that page. On another page called 'Contact' I need the menu block title to be 'Contact'.

I hope you understand me and can help me ;)

I've tried this in my template.php but it's not working:

function hook_block_view_menu_block_menu_peanuts_alter(&$data, $block) {
   $data['subject'] = drupal_get_title();
}

Thank you for your help (and your module).