Consider

[DanaC]

I'm inclined to agree that's where the ultimate responsibility lies, but whoever owns the dog that does the big damage would surely feel some responsibility and want to contribute ( as indeed was the case here).

My guess is that the situation is also wrapped up with the Mum staying at the house when it's not ideal thing. I love my mother dearly, but truly I think mothers and daughters don't live well together as adults. Short term yes, but tensions quickly start to simmer even with mums and daughters who are very close.