Cancellation of Gift Deed

1. My Father Expired in March 2020 without leaving any will. 2. He had a self acquired Property ( House In Bangalore) built on 34 x 40 site. 3. My 73 years old Mother lives in that house. 4. Son Lives in Bangalore & daughter lives in USA , estranged from Parents for last few years. 5. In Oct 2020 Mother Signed a Gift-deed , gifting the property to her Brother ( Our Maternal Uncle ). 6. Now due to disagreements with her Brother ,she contacted us her children to file some legal action so that her Brother will not get the property. 7. Our Lawyer advised that we children have to file a case against the Mother , we do not want to do that. 8. We were advised that Mother can contest as a Senior Citizen. 9. What is the process for contesting as a senior citizen . 10. If we contest as a Senior Citizen, do we also need to file as Stay Order ? or can this be avoided 11. If the stay Order has to be filed , what is the Process ? 12. Can Stay Order be filed by 1 of the children or is it mandatory for both children to file ? 13. Please advise. Thank You.