Will declaring my mother as my dependent affect her California Medicaid benefits?

Medicaid eligibility rules do not count a child's income when evaluating eligibility of the parent. Thus, if in fact you have paid for support of your mother, and are able to take her as a tax deduction as a dependent, that is an IRS rule and is separate from the Medicaid rules. You can research this by looking for "child-to-parent deeming Medicaid" for your state. You will find that in determining Medicaid eligibility of a child under 18, indeed this IS deeming from the parent to the child, but it's never the other direction.

My mom lives with me now after her stroke and is medicaid eligible. They do not factor in our income. If you are paying more than 50% of her support to claim as a dependent be careful she doesn't accumulate too much cash in her acct or she wont qualify. We allow my mom to contributr to household expenses in order to spend down her money

We have my MIL living with us and she is able to have her own separate claim from ours. We are on Medicaid ourselves, but we file as a separate household on our application. She is only on there as living with us as a renter. She is able to have her own case and we have ours. Her only income is social security, so this helps her with being able to get long term care too. I am not sure about how it works if you claim her as a dependent though. I think you will also have to check with your state to find out. You can go to your state's DES website and it should have more answers there. Best wishes to you both.