You are correct; the account became hers upon his death. I would suggest going to the bank with certified copies of the appropriate docuemntation and asking the bank to release the documents.
If they won't do so, yu will need an order from the court requiring them to do so.
I practice only in Florida. So my comments are only applicable to situations involving Florida law. In general, the laws of other states are similar, but there is no guarantee of this. It is advised that you consult a lawyer who practices in the state where the issues have arisen.
If you are the executor or Personal Representative of an estate you should be working with an attorney. Please direct any and all inquires regarding this estate to your attorney.
In general, all joint accounts become the sole property of the surviving owner upon the death of the joint holder and therefore are not part of an estate.
Answer does not constitute legal advice. Please call (727) 471-0039 or contact me at firstname.lastname@example.org, if you would like to discuss your Florida legal matter further. This answer is provided for informational and/or educational purposes only, does not constitute legal advice, and does not create an attorney-client relationship. Adam is a Florida Attorney practicing in areas of Estate Planning, Elder Law, Trusts, Probate, Guardianship, and Business Law. Actual legal advice can only be provided after completing a comprehensive consultation in which all of the relevant facts are discussed and reviewed.
No-probably not without court order or cooperation.
The answer given does not imply that an attorney-client relationship has been established and your best course of action is to have legal representation in this matter.