Does the guardianship of a father suffering from Alzheimer's transfer to his eldest adult son, or does it remain with his wife based on an old general power of attorney?

The matter must be referred to the Sharia court to place the father under interdiction, as it is the authorized body to rule on such matters. If it rules for interdiction, it will appoint someone to safeguard his wealth. The guardianship of the interdicted person's wealth falls first to his father, then to his father's executor, and then to the judge or ruler. The father's agency for the mother becomes void upon his interdiction, because interdiction prevents him from disposing of his wealth, and consequently, he cannot delegate anyone else to do so.