...for obvious reasons the office wants to allow deposits.
There isn't any way to fill it out correctly; the money belongs to the decedent's estate, not the decedent. I don't know diddly about CA law, but am willing to guess that your bank needs a court order naming the personal representative and an EIN. Also, I hope "the manager" isn't still signing checks.
However, what your bank really, desperately needs is someone running "the office."