Fear of eviction and bad living conditions.

My mother lives in Hayward California, and is currently renting part of a house. Specifically the basement of a larger home. It is not built at all to code and is horrible to live in. The bedroom is a concrete box with only one door and no windows. Recently almost every outlet went out and upon further investigation I found that water had leaked in through an exterior wall and into a wall outlet shorting it to a point that inside the outlet box was only charred wire and exposed copper wire. It's not an easy or cheap fix and I want my mom to get the LL(landlord) to fix this and all the other issues, but my mom fears eviction as the LL is horribly mean and unwilling to spend money. What can we do to rectify the houses problems without the threat of eviction?