Is it permissible to give charity on behalf of the owner of a cow that was accidentally killed forty years ago, or to give him money without informing him of the reason, to avoid family problems? And should the value of the cow be estimated at its price then or its price now?

Whoever caused the destruction of a cow must repent to Allah for delaying the fulfillment of the right. If the cow was destroyed, the obligation is to guarantee what was destroyed with a similar equivalent, if possible. If a similar equivalent is not possible, then with its value. The correct view is that an animal is guaranteed with a similar equivalent as much as possible. If it is not possible to provide a similar equivalent, then its value at the current price is binding, along with compensation for the change in currency value if a long time has passed. It is not a condition to inform the owner of the cow if there is fear of harm from doing so; rather, it is sufficient to give him the money without informing him that it is the value of the cow.