Is it correct to give a flat as a gift to grandsons?
بسم الله الرحمن الرحيم
(Fatwa: 180/180/B=2/1439)
Yes, it is correct. It should be given in the custody of his wali (custodian) and in case he is adult he shall take it into his complete possession. However, it is better if its bainama process is also completed.
However, if there are other grandchildren or sons then they should also be taken into consideration.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband