Is deferred dower (mahr mu'akhkhar) due to the wife after the husband's death, and how is this deferred dower calculated if more than 40 years have passed since the marriage contract?

The deferred dower is a debt owed by the husband. If he dies before paying it, it must be settled from his estate before its division, just like any other debt, according to the Almighty’s saying: "from after [there has been satisfied] any bequest he [may have made] or debt." The wife’s right to inheritance is not forfeited. If the deferred dower is existing money, it is given as is. If it is missing, its value is given at its last price before its loss.