Is it permissible to give charity from my mother's pension, who is afflicted with Alzheimer's, according to her will before she was afflicted?

A person afflicted with Alzheimer's or mental incapacitation has their assets placed under interdiction (guardianship), and nothing is disbursed from them except for their benefit, such as expenses for themselves and those whose maintenance is incumbent upon them. The interdiction is imposed by a judge. If there is no Shar'i court, the children choose who will manage the assets, because guardianship belongs to those who are closest to the interdicted person. If the mother bequeathed a charity from her pension, then if her intention was the charity after her death, the will is valid and executed within the limits of one-third of the estate. However, if her intention was the charity during her lifetime, it is not permissible to execute it, because the loss of her mental faculties invalidates her financial transactions. It is not permissible for the guardian to give charity from the assets of the interdicted person, because the guardian's disposition must only be for the benefit of the interdicted person, not as a donation or a gift. The guardian must spend from the interdicted person's assets in a reasonable manner, without extravagance or parsimony.