Legal Question in Family Law in California

It is the last Will which controls the distribution of property designated by the person who dies. The prior Wills become irrelevant. If there was no decree of divorce, then he would be considered still to be married at the date of death. If the agreement was that on divorce he would get "X", no divorce had occurred so the agreement is no longer binding. she is entitled to half of the community property as the definition of community property is that each spouse has a half interest. He could give by Will his half to another person, but if the Will does not include the community property that asset would go by the laws of intestacy which means your mother would get his half.

Your mother is going to have to spend the money to hire an attorney to determine what the actual factual situation is so that the law can be applied to it.

Your mother needs to consult with an attorney to review the facts and the papers.