Can agricultural land gifted by mother and RTC obtained in my name be revoked ?

My Father earned and bought agricultural land in name of my mother. Later he bought more agriculture land in his own name. Later he expired without a will. His piece of land is also taken over by mother in her name. I am eldest daughter and have 2 siblings - 1 sister (has 1 daughter) and 1 brother. Another brother expired (has 1 daughter). Later mother gifted small portion of land to me and I obtained only RTC in my name years ago, but not yet 'pucca podi' nor mutated. 1} Question is can mother revoke the gift deed and reclaim the land back from me ? Will my signature be necessary for this? 2) If I don't give my signature yet can she cancel the gift deed and take back the land without my signature ? 3) Can the daughter of my expired brother claim her father's share ? 4) What are the ways to keep my gifted share of land in my name ? 5) Is it possible to do the pucca podi, mutation and officially register my share of the gifted land using the registered RTC alone ? Or is it necessary to have the signatures of mother ?