What must we do to clear the conscience of our deceased father who found a purse containing money (45 dinars in 1965) and did not return it to its deceased owner? How do we estimate the current value of this amount, knowing that it was equivalent to 112 grams of gold at that time? And is what our father did permissible, in spending 5000 dollars given to him by his sister to be spent on the needy, as he spent it on us under the pretext of our need for it?

The father sinned by concealing the money he found in the pouch. You must निकाल (remove) it from his estate and give it to the heirs of the money's owner. If she has no heirs, then it must be given as charity on her behalf for the benefit of Muslims.

The value of the money should be calculated according to its purchasing power at that time, either by considering the value of essential goods or the price of gold at that time.

As for the money the aunt gave to the father for charity, which he spent on you, there is no sin upon him for it if you were in need.