Challenging a gift deed
My mother on good health and mind wrote a conditional gift deed on my name dated 07.11.2012 in the presence of my father. According to the conditional gift deed, myself and my mother have equal right upto her life time after her the entire property is upto me. It also mention that she has no right to alter the document. The property is basically my fathers self acquired property which he give it to my mother as a gift deed in 05.04.1994. After my fathers death, my mother came to know that all other properties also come to me by fathers another gift deed. Due to sisters pressure now my mother threaten me that she is going to challenge the gift deed on the ground that she is not in normal mind and health and my father fool her and force her for the document. but its a false one. She threaten me that she is going to file the case on 02.01.2016. is it effective sir? is the gift deed can be cancelled? In net i found that challenging a gift deed is not possible after 3 years, is it true sir?