"When my daughter passed 2 years ago she and her dog were living with me. She's an Australian shepherd mix and a rescue. She is a fear biter and I haven't had her to the vet myself. I'm not sure what to do.”
My best advice to you is to find a veterinary practice in your area that is certified "Fear Free." This is something relatively new, but many practices are embracing it. These Fear Free practices use a variety of techniques to make a visit to the vet easy and pleasant for your pet. They even use calming medications, if necessary, that you can give at home before going there, to relax your Aussie mix before she even heads out the door.
I would call and talk to someone at that practice, tell them your situation, and see what they suggest. Fear Free practices are willing and able to try various things until they find what works best for your dog.
If you are unable to find such a practice, please get back to me, and we can talk about how to get your dog comfortable wearing a muzzle. Muzzles, obviously, prevent the dog from being able to bite. But, since a dog is smart enough to realize that they can't bite when they are muzzled, they actually calm down some once the muzzle is on.
Good luck. And kudos to you for caring for your daughter's dog, even though she is a bit of a tough customer. We all need love, the easy ones and the tough ones. I applaud you.