If she is a signer on the account she is very likely also an owner of the account. That would mean that she could do anything she wants with the money at least as far as the bank is concerned. Funeral expenses should be paid by the estate. If asked to return the money she should also file a claim against the estate for that expense. I doubt the PR could make her pay the money back.
Hello. I am sorry for the loss of your parent. An authorized signer on a bank checking account typically is a co-owner of the account. Generally, a co-owner of a bank account has the right to use of the monies.
Minnesota licensed attorney