Joint property-Husband expired

Hi My name is Raisa Khatoon.My husband expired.I have only 2 son. I have a joint property -a flat 2bhk in rajarhat kolkata with my husband.He expired in march.The registration is not done.i have fully paid all the instalments.The builder (LOHARUKA Group Rajarhat) is not giving me key.Telling u will get the key only after registration. I m ready for registration but he is saying that ur husband expired and have no son only 2 daughters and since u r muslim and as per muslim law u will be entitled for only one half.Other half will be shared between ur daughters and with ur husband's family like husband's brothers and their sons.Or else u have to bring NOC from ur husbands he right? I want registration in my name.What is the procedure? I have agreement paper and all the reciepts of the amount paid.My daughters also want that the registration to be done in my name.They live abroad.So i m alone in kolkata india and want help.The best and easy legal way to get my flat.Its my husbands dream home. Thanks & Regards