is NOC required from my aunt

since he had died intestate your grandmother and his children would get equal share in the property.so your dads must be 1/3 rd share in the property.try to arrive at a family settlement to workout your share and if its not possible to arrive at a amicable solution file a partition suit to determine the share

grandmother can gift her share alone to you or your dad and if your aunty doesnt want any share then she can relinguish her rights over her share