Will law support us in getting this house?

My dad built a house in our village (west Bengal) and we stay in Mumbai, this house was built on my grandfather's property, grandfather had 2 sons and 1 daughter, my dad was the eldest amongst them. he incurred every education and marriage expenses of his siblings, and even gave money to his parents. everything in that house is done by my dad, and now my dad died during covid, he left us nothing but that house which wasn't even in his name. my grandmother grandfather and uncle aunt they don't talk with us after my dad died, they say my mom killed my dad, soon after my dad's death my grandfather also died, now I've come to Village and asked them for property deed which I needed for my SC caste certificate, my grandmother straight up denied to give me those papers. things flared up because my mom is the rightful owner of this house now but we don't have the evidence that my dad built this, since grandfather died, the land will be shared among 4 people- grandmother, my uncle and my aunt and my mom (since my dad isn't here) my dad built the house on his share although it isn't in his name he still built the house because he knew he wanted this part of the land, and now my uncle, aunt, and grandmother is denying this fact, tell me am I wrong for asking this whole house, it's built by my dad and my mom and I are the rightful owner