Is it permissible, in Sharia, for a daughter to pray for the death of her sick mother if her death would be better for her?

This supplication is not legally required for someone suffering from severe harm or illness; rather, it is among the permissible matters. It is more complete not to say it for oneself or for others, based on the saying: "If there must be a wish for death," and it is better to ask Allah for well-being. Supplicating with it is not considered disobedience, as there is no difference between the sick person supplicating for themselves or for others, especially if it is motivated by compassion and mercy, and entrusting the matter to Allah.