Is there any organisation/deprtments to help the children who are victim of mental torture by old parents?

after the death of my father,my mother is behaving very strange manner and in collusion with my younger sister my mother trying to deny me the cash share from the bank account and deposit which was in joint account with my father .She has made my sister joint account holder in those account where I was nominee. further she is trying to make issues out of non -issues calling me names as greedy etc spreading false rumour and allegation to other relatives and I feel very depressed