I don't think the puppy passed away because it was taken from it's mother at 7 weeks. Where I live generally puppies are taken from their mother at 6 weeks. (I'm not saying that it's right but it happens every day) It sounds like something was seriously wrong with the puppy. What did she do with the puppy? I know a lot of breeders require an autopsy in order to refund your $ or give you a new puppy.
I'm so sorry for your friends loss that is incredibly sad
