Non-payment of rent

Respected Sir My parents who are very old had rented a flat in their building to a family with 11 month lease. Initially the daughter and mother of this three memeber family had approached my parents without informing us the family head and the bread earner is paralyzed due to cerebral stroke and their is no earning member in the family. But at the time of signing of lease the paralyzed person and half disabled mad man signed the lease. The family has stopped paying the rent for last six months and are arguing that since the paralyzed person can't work they are unable to pay rent. Meanwhile, the 11 month lease has expired and immediately they have been served notice to evict the apartment both on the grounds of non-payment of rent ( 6 months) and lease completion. They are not vacating the apartment. What should we do ? Please help us with your suggestion. regards Amitav