Is it permissible for a widow to give her Zakat money to cover the medical treatment of her granddaughter who suffers from a chronic illness, if the granddaughter's father is unable to afford the costs of the treatment?

It is permissible for a grandmother to give her Zakat money to her needy grandchildren for treatment or other purposes, as long as they are eligible for Zakat and she is not obligated to financially support them. This is according to the Maliki school of thought. The grandfather is not obligated to support his son's child, and the obligation of financial support does not extend to grandchildren, nor to grandfathers and grandmothers, according to the Malikis. Rather, it is limited to the first degree of descendants and ascendants (father, mother, son, and daughter). Therefore, a granddaughter who needs treatment is considered poor and eligible for Zakat, and she is more deserving of it due to her dire need and being a close relative.