Are you sure it was "subscriptions" like from the subscriptions.php script vs. Threads that she'd added to her favorites?
If you remove access to a forum, I'm not sure, but I think their favorites remain unchanged as it would be pretty complicaed to check every favorte against what forum it's in.
If she had email replies to favorite threads, she might still get those. In that case, she'd have to remove the favorite from myhome.
