Shady Tenant trying to purposely causing problems

HI guys 

Im looking for advice on my tenant, the situation is that I have a FHEPs tenant which is a NYC subsidized voucher program that pays all the rent for my tenant, the rent has been on time but the issue is the tenant. The tenants are constantly complaining about every little thing in the apartment, I make repairs and constantly communicate with them. However now it is apparent that they want money out of it in some way. This guy "falls" in the building, saying the steps need to be repaired,  I checked and there is nothing wrong with the steps outside the house. It has been the same step the whole time he is living there and now he claims theres an issue and that he rolled his ankle. I was on my way to make more repairs to the house and his apartment when his wife is now saying that he is in the hospital for the fall. It is obvious they are moving shady and looking to sue. Not exactly sure what is their game but wondering if I could be held liable for him falling and what to do with him as a tenant moving forward? Any thoughts and advice is appreciated. 

Thank in advance!