Any California bees know a bit more about renters’ rights than I do?

My parents rent out rooms to help pay for their mortgage.

Recently (this is all according to my dad) a renter left large stains on the carpet, stains on the bathtub and sink that according to my dad they can’t get out. My parents spent $100 on professional carpet cleaning services for the room and they cleaned the bathroom themselves.

My dad asked this tenant to leave and gave him two months notice.

According to my dad this tenant had multiple cars and made a living off fixing up cars and selling them. He says that the stains are due to his car maintenance work.

The tenant paid $500 security deposit and asked for an itemized receipt with before and after pictures. According to my father the tenant wants his whole security deposit back and has threatened to sue him if he doesn’t (but I was not there for this conversation).

My dad wants to charge him $100 carpet cleaning fees (which they hired someone for and have a receipt for) and $200 for labor costs (my mom, dad, and brother cleaning the bathroom and etc.)

I feel lost at how to help him with this.
A simple typed up word doc receipt should be fine, right?
$100 carpet cleaning
$200 labor cost
$300 total

What about the tenant’s request for before/after pictures? Is that necessary?

My parents have had multiple tenants but this is the only guy making a huge mess and also giving legal threats and I think my dad is both furious and a little worried.