You could probably retrieve the emails but it would be an very expensive and time consuming. The old emails that were BC won't have any other email addresses visable in them. The data that was on the hard drive that was wipped might be recoverable but that is always a time consuming and expensive process. The only think I might suggest is to ask AOL if they keep any kind of a sent log. Then maybe she can recover some of those email addresses via that sent log. They might still have that information even though the account has been closed.