Is it permissible for children to reclaim items they purchased with their own money in their mother's house after her death, knowing that their father intends to remarry?

If you have gifted something to your father and he took possession of it, then you are not permitted to revoke the gift. However, if the gift has not been transferred, then the money belongs to you, and you may take it whenever you wish. Your father is permitted to benefit from it to spend on himself and his wife, due to the Prophet’s (peace be upon him) saying: "You and your wealth belong to your father." A father is permitted to take from his son's wealth what he needs for his own sustenance or for the sustenance of those whose support is incumbent upon him, even if the son does not agree. Being dutiful to one’s stepmother is part of being dutiful to one’s father. Using a shower is permissible if it is for something beneficial in religious and worldly matters, and forbidden if it is for something that is not religiously permissible.