Where can I find low-cost housing for an elder with Parkinson's in Orange County?

I don't have resources in OC, but if start by calling city housing departments, talk to the person in charge of RAP (rental assistance programs). Many cities have emergency funds, although they are dwindling. That person should also be knowlegeable about roomate matching services for seniors. You may also reach out to different groups such as St. Joseph's in Southern California - they manage homeless prevention programs.

good luck. I will assume that there is no mediating with the daughter and kicking him out is not dropping him at the curb with his stuff. If that is the case, and he is frail/elderly you may want to call an APS caseworker and talk about options for emergency placement

good luck. reading your story makes me realize how lucky we all are - your client is lucky to have you going to bat for him.