Clarifications regarding ancistral property

Sir, My mother (widow) aged 74 years has around 3 acres of land in different areas. This ancistral property is from her grand father and my father's grand father. We are 3 children and i am the youngest, married without any children. My elder brother is married and has a child. My sister is a divorcee without any children. My brother's family and divorced sister are staying in the ancistral house where as due to my job i am staying in a nearby town around 70 kms away. My father passed away around 27 years back. Now i want to know the following : 1. Whether my mother can sell any of the above ancistral property without my consent. 2. Whether my sister has got any right in the property. 3. Since i am away, whether she can gift the above property to my bother or sister without my consent ? 4. In case she wants to do so ? how can i take back my share ? 5. What precautions i should take well in advance in order to safeguard my ancistral property share. Hope you would guide me in this regard please.