Depends on a lot of facts that you need to find out more about from Mom (if she knows). Dad can easily freeze you out if he wants to by using a technique in a will called a "Marital Trust." He can transfer all of "his" assets (not joint assets with Mom also named on account - Question #1 for you) at death to a trust that will say that Mom can get income for lie and perhaps tap into corpus/principal if she needs health, maintenance and support items (Question #2 - what does the Will say?). Dad would hire a professional trustee (like a lawyer or bank) who would be in charge of the purse strings. (Question #3 - what does Will say) It could also say on death of Mom the assets go to X, Y and Z...whomever Dad wants if Mom was gone. (Question #4 -what does Will say?).
with that being said, if Mom is on the Home Deed as Joint Owner w.r.o.s. then she will automatically own 100% of the home if Dad dies first and there is nothing in his Will that can change this immutable fact. Same thing if they have joint bank accounts, brokerage accounts or payable on death ("POD") accounts held in his name but having this designation on file with the financial institution holding the account. Good luck in your detective work to sort out what you are looking at.
p.s. Maybe Dad is just saying he is freezing you out because he wants you to work harder to move out and make your own life and not be dependent on him....,more frustration with you than a real intent to cut you off at the end of the day when he dies .... that I cannot advise you on but it could be true -- one never knows.
My answer is not intended to be giving legal advice and this topic can be a complex area where the advice of a licensed attorney in your State should be obtained.
The fact that your parents have lived a long time in California means that unless there are really strange facts, at least half is your mother's to control as she sees fit. As to your dad's share, that is hard to say. He could put it in trust for your mom's life and then have it pay to charity or other family or friends. If he gives it to your mother, she should be free to do as she pleases once your dad is gone.
Your mother should see an estate planning attorney now to determine how her assets should be held and what rights she has.
If your parents hold assets as joint tenants or community property with rights of survivorship, those assets will pass to your mom outright by operation of law without regard to any other documents your father has drafted.
I hope that helps in some manner.
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