Living with severely disabled parent and requiring Housing advice.

I live in Northern Ireland and am on PIP and ESA (Support Group), I also have a works pension which I receive monthly. I am soon to be 60 years old. I have been Carer for my chronically disabled mother since 1997, living with her all that time and before. My mum took a very dense stroke and I have been caring for her ever since. I have been told that my mum would be placed in a Nursing Home if I was not living with her and since she has always been terrified of that prospect I have been required to stay with her.  We moved to a Public Authority Pensioners bungalow in about 1999. My mum is now 90 years old and regrettably, approaching the end of her life. My mum is the sole tenant of the property, I have no basic rights of tenancy. I would like to know if I could be included on the tenancy as a joint tenant so that I can remain in the property after my mum's death. Would I be required to pay rent and if so how much. The bungalow has some adaptations to suit my mum's needs e.g. overhead hoists and shower room rather than bath room. I am basically afraid of being evicted from my home after mum's death. In Northern Ireland Public Housing is not governed by the Councils, we have a local government body called the Northern Ireland Housing Executive which administers public Housing.