When my MIL died, the mortuary notified social security. Supposedly a standard procedure. Because they (SSI) were depositing the monthly SSI into my MIL's account, the bank was notified and they basically froze the account. My wife was on the account and was paying bills monthly and making deposits. But once they knew that the OWNER of the account was dead, she was frozen out. IMHO, if my wife was a co-owner of the account OR if the beneficiary of the account was my MIL's trust, it would have helped a LOT. Just having access to the account ceased when the owner died. Same thing for the Schwab investment account.
So, my advice is go to an estate attorney and make sure that you will have access after death and make sure (if there is a trust) that the trust is the beneficiary of all of the bank and investment accounts.