بسم الله الرحمن الرحيم
(1) The amount deposited in LIC became inheritance of your uncle which should properly be distributed among the heirs, only the son is not eligible to use that money. While the extra money received or to be received on LIC should be distributed to the poor and needy ones without an intention of reward rather with an intention to get rid of the malicious money. It is unlawful for the heirs to use the extra money.
(2) You can marry the daughter of your uncle. But you should keep on trying to rectify the heirs of the uncle to possible extent.
Allah knows Best!
Darul Uloom Deoband