Self Owned Property .does It Need Her Children's Signature To Sell

1) 70 years lady self-owned property does she need her children's signature to sell the property. 2)This lady had given power of attorney to her daughter in 2005 for case .only for the case. and the case is settled. but still, her daughter is claiming that her signature is needed to sell the property. or else she will file a case not to sell the property. 3) This lady had bought this property from my grandfather. and now I am buying this property back. I have paid her advance of 5 lakes through cheque and got a sale agreement. Now the children are fighting with they mom telling we will go to court. Now that lady is confused and afraid. 4) Now if that lady does not want to sell the property. what to do? please guide me