Is it permissible, in Islamic Law, to place the father’s assets, who is afflicted with Alzheimer’s, under legal guardianship and to hold his wife accountable for her dealings with his money over the past five years?

Legally, a ruler is permitted to place an interdiction on an elderly person if their intellect declines and they can no longer manage their wealth properly, as reported by Ibn Abbas. If your father is in such a condition, there is no harm in submitting the matter to the Sharia courts to decide whether or not to place an interdiction on him. Your enforcement of the interdiction, if ruled by the court, will not be considered anointing, provided you treat him with kindness and benevolence. As for holding the wife accountable for her previous financial actions, the matter should also be submitted to the

courts for consideration after the interdiction has been established. However, if the issue can be resolved amicably, that would be preferable.