House transfer to three children name in Delhi

Hello we are based in Delhi. 1. My grandfather has a house, he passed away long time back and now it should have been automatically transferred to my grandmother's name ? 2. My grandmother now wishes to transfer this house to her 3 children. It's a 30 years old house, 3. We are not sure if it was made via huf ? What is the implication of it ? My grandfather had 4 brothers who have all password away. 4. Also what the amount that we would need to pay if we get this house transferred ? Kindly let us know full detail procedure ? 5. If we don't get this house transferred and my grandmother just makes a will , can we avoid paying any charges ? Thanks and regards.