An oral one year lease is valid, but hard to prove. If you have a valid one year lease, your landlord cannot require you to change the terms mid-lease. If you do not, the landlord can change your lease terms by giving proper notice.
Here, it appears you may have a sublease with the master tenant and the landlord is asking you to sign a lease directly with her. You are not required to do this, but your landlord, the master tenant, may be in breach of its lease for renting to you. You will probably need to review the whole situation with a lawyer to get a definitive explanation of your rights and obligations.