Claim a part in family

Last year in Aug my father passed away due to cancer before his death he debarrded my elder brother along with his wife and his daughter from family property due to behaviour issues through newspaper add and also wrote a will in favour of my mother followed by written notification to local police as my brother along with his wife and his wife's family were threatening for money . But recently few days back my brother also passed away in an accident . He was jobless from last 2-3 yrs and was under depression.Taking due advantage of this my brother's wife along with his relatives who were huge in no.s pressurized us to give my brother's wife and his daughter the share in property as when my brother's dead body was lying and did not let us do his cremation unless we sign the agreement that we will give them 50 lakh rupees. We were pressurized so much that we had to sign the agreement as at that point of time we could do nothing and even police also adviced to do settlement . Pls note my mother is housewife and is 57 yrs and after my father m taking care of family expenses and m married and work in private company earning around 40 k monthly so I m not in position to pay such huge amount . Also am not in position to go ahead with court case but need to make sure of family security so that nobody can again claim share in family property in future neither my brother's wife or his daughter after she has become adult . M ready for settlement with amount as lowest as possible but need settlement with proper paperwork .