How sad but at the same time....she may have done the puppy a big favor.
It sounds like she really wasn't ready and they're a huge commitment. I know it's been said but anyone who is going to take on the responsibility of ANY puppy should always do their homework....but at least he's in a home where he's loved. You can be happy for him in that aspect...It sounds like you would have been a great grandmother for him though..that's too bad.
I hope he has a great life in his new home