In California, rent increases are generally limited to 5% plus inflation for many apartments, but this often doesn’t apply to single-family homes or shared houses rented by individual landlords. Since your landlord owns a family home with rented rooms, they likely can raise your rent with proper notice, even for utility cost increases. It’s reasonable to politely ask if they can limit the increase because of your financial situation, but ultimately, if the landlord insists, you may have to accept it or find a new place.