What would be the legal remedy against the bank for me in order to get the money?

I am a beneficiary of my late Aunt's living trust. She died in May and I have received a copy of the trust from the law firm in California that is handling things. Due to a lack of communication between the firm and myself, I'm not sure what's going on. The last I heard was that the bank in California that has my Aunt's Individual Retirement Account funds is refusing to release the money because she didn't list any beneficiaries on the paperwork they have on file. Can a bank do this? Thank you for your time.