If the relatives of the husband who hold the gift are her relatives as well, like cousins, then they are not allowed to ask for the return of the gifts. If they are not her relatives and the gift items were not used, then they are entitled to have them back.
No individual has the authority over his/her body after death. So they do not have the right to donate â€“ in the will â€“ the organs to anyone after their death. Yes, it is permissible to use the organs of a deceased person if the survival of a Muslim life depends on such usage.