Is it permissible for a father afflicted with Alzheimer's disease to be the guardian of his daughter in the marriage contract?

If your father is incapacitated due to illness, he is considered to be in the same position as someone mentally deficient, and his guardianship in marriage is not valid. In this case, your adult son has more right to give you in marriage than your brothers. Your brothers do not have the right to refuse to give you in marriage. If there is no guardian, then refer the matter to the Sharia court, for the ruler is the guardian of one who has no guardian. We also note that caring for one's father is the responsibility of all his children, especially in old age, for it is a gateway to Paradise.