I suggest that your mother seek another attorney.
First of all, your mother should be the executor, not the lawyer. However, California law does provide that he cannot "double dip" - that is, he cannot take both the executor's fee and the legal fee. So as long as he is representing himself, there should be only one fee to pay (there are certain exceptions, however, and he has an obligation under the state bar rules to explain this to you).
If the bank account was in your father's name alone, there MIGHT be a need to probate the estate. But more likely, the lawyer should have either filed a "Spousal Property Petition" or he should have filed an "850" petition (that's a section of the probate code that sometimes can be used to avoid probate).
ASK the lawyer what his fees for a Spousal Property Petition would be. Usually they are considerably less than the cost of a probate. In a $335K probate the executor and the lawyer can each charge approximately $9,700. If the estate is worth $565K, the fee would be over $14,000. A Spousal Property Petition should be $3,000 or less and should take considerably less time.
I would be willing to assist if that would be appropriate. I have handled probate court proceedings in many of California's counties.
This information is not intended to substitute for professional legal advice and does not create an attorney-client relationship. You should accept legal advice only from a licensed legal professional with whom you have an attorney-client relationship.
I concur with Janet. This is the kind of thing that gives the public a bad impression of attorneys in general.
However, some of your assumptions are incorrect.
First, the money in the bank account doesn't automatically revert to the spouse. The account would have to have been titled appropriately (i.e., jointly or with Pay on Death or Transfer on Death designations) to pass from your father to your mother on his passing. The law and institutions put these hurdles in place to ensure that the right people get the money.
Second, if assets are inherited once does not mean they never have to be probated again. For example, if a father owns a house and dies without a will or trust, the house needs to be probated to pass to his only son. If the only son dies without a will or trust, the house needs to be probated again to pass to his only son and so on. Probate is a legal process for clearing title so it needs to be done at each death.
Please make sure your mom consults with another probate attorney immediately and gets some straight answers to your questions. Good luck.