How can I get guardianship of my father if he lives in San Diego, CA and I live in Georgia? What step would I have to take to make it legal?

If you can do DPOA as Marcia suggested that would be the simplest.

But if dads not capable of doing a dpoa, then that usually means going guardianship. Please clearly ask attorney IF CA courts prefer or require anyone getting legal guardianship need to be a legal resident of the state of CA. If so, then you are going to need to have a CA atty named as guardian.

Judges, I’ve found, really really want guardians, Executors to be a resident of a the county that is within their jurisdiction. If not, then your attorney of record needs to be. also if you find a guardianship is needed, it will be significantly more expensive than the costs of DPOA.

I think she is legally still his wife. If your dad is still legally competent, he can just sign papers to give you Power of Attorney for his finances and health. He is considered to be legally competent until a court determines that he is not legally competent. So even if he has beginning dementia, you can probably still get these forms put into place. You need to consult a lawyer in California to see how to best proceed. A lot of them will give you a free consultation.