Oh man. I hate those decisions. I have tried all three versions and I would caution against boarding at a vet unless it's an emergency b/c vets will have sick animals and you just don't want to risk that with any age bulldog, especially a pup.
Technically, your dog will be safe in the other two situations, unless the dog nanny is irresponsible. If she has good common sense and wannts to keep her business, she should be ok. I use an experienced dog sitter who is also a certified trainer. But we always try to take Lupe with us, or cancel. Good luck!