What are California tenants' rights concerning guests?

My boyfriend pay $400 a month to live in his family’s multi-family home in El Cajon, CA. His parents are the landlords (they don’t have a business license), and he works for his step-dad’s construction business. I’ve been dating him for a year, & after his sister & I had a falling-out a month ago, his mom, who favors her daughter over him indefinitely, has decided to forbid me from ever coming over again. His sister is not a paying tenant & doesn’t even live there.
According to California law, is he able to have me over anyways? He does not share any communal space with his family except a hallway. He is a paying, lawful tenant, & feels like his parents can’t call the cops on me for criminal trespass if I am his personal guest he has invited over.