Is prayer obligatory for a father suffering from dementia who is unaware of his surroundings? Will his supplication against his children be answered with ill, despite their care for him? What should a daughter do who sometimes raises her voice at her father and then seeks forgiveness for it?

Prayer is not obligatory for one who has lost their mind, because the basis of accountability, which is intellect, has ceased to exist. The questioner is obligated to obey her father to the best of her ability and will not be held accountable for anything beyond that. She must treat him kindly and not raise her voice at him. Allah Almighty says: "If either or both of them reach old age with you, do not say to them [even] 'uff,' and do not repel them but speak to them a noble word."