Is it legal for a California landlord to charge a $50 monthly fee?

I recently reported my property manager for negligence to to her management company and now I find my self with a $75/month rent increase.( No one else got notice of a rent increase). But what I am really concerned about is an additional $50 monthly fee for being on a month to month lease. The property manager knows that my company is going through a merger and that my job could be eliminated so I can't sign another 1 yr lease. Almost everyone here is on a month to month but I am the only one that just got notice of the $50 monthly fee. Is she violating fair housing laws and what can i do about it?