My neighbour is harassing me with a group of other neighbours

I live with my mother in railway government quarter on the basis of compassionate grounds after my father's recent death. The man living on ground floor (since we are on first) threatens us to empty the quarter along with few neighbours which he recently convinced. The problem started when my father died as an SSE he started complaining for water leaking into his house from our tanks (tanks are on terrace) he even managed to do something so that we don't get enough water. I even went to his house and gave my number so that he can inform in case of any water related issue. (everyone in the colony has mortars for filling water including us and we turn it on at every 6 am and pm) He walked up straight to our house saying that we should turn off the mortar even when we had not enough water to drink. Then he started complaining that we were so loudly arguing that it disturbed him and he managed to get neighbours on his side. What exactly happened is that I'm a 21 year old girl and in college. My mother being a responsible single mom trying hard to deal with everything and then the day she was screaming at me for my bad behaviour he just walked to our home and rang the bell. Then also he didnt stop and called all other neighbours with him.we got so depressed mother even tried to attempt suicide that day. He threatened us that he will complaint against us and we have to leave the quarter. Their behaviour is extremely humiliating and threatening.