By "Let her die" you mean "Kill her", right?
There is a difference between killing someone and not saving them. If I was in her condition I'd want them to stop delaying death. This case is weird and I don't know why the government is even involved. It would be so much easier if she had written something that said you know "if i am braindead you can end my suffering". Unfortunately she didn't and it comes down to the husbands wishes vs the parents wishes. This one is in a stalemate. Perhaps they should settle this over rock paper scissors.