My question involves landlord-tenant law in the State of: California (Los Angeles)

I am trying to find out if this situation is legal and what we may possibly do to fix things.

A woman has subleased out 3 rooms of an apartment that she has been living in as a renter. Now, she has moved out and owns a house 5 blocks away. However, she has taken over the living room, kitchen and dining room as her office for her business (she does run her own business as an event promoter). She doesn't live there but has taken over most of the house with her "business".

From what I've gathered, she is not paying anything towards rent or utilities and refuses to give any of the subleasers a copy of any utility bill or total rent due for the apartment. Talking to a neighboring unit they said that the rent is much less then what the three subleasers are paying in total so it seems that this woman is making a profit.

So my questions are:
Can the woman have free access to the house b/c her business is there, even if she is not paying any money towards the rent/utilities?
- Is that legal from a business point as well to run an office in a residential house
Can she refuse to provide any bills to the subleasers?
If she is allowed to use the house, is there any legal way to restrict her to her "office"?

thank you very much for any advice or tips