What is the legal ruling regarding the failure to fast by a sister suffering from brain atrophy, who has no hope of recovery and is not aware of her surroundings, and is she required to feed a poor person, and what is its value in Saudi Riyals?

Fasting is not obligatory for someone who has lost their mind, according to the Prophet, peace and blessings be upon him, who said: "The pen has been lifted from three: from the madman whose mind is overcome until he recovers." The same applies to prayer. Ibn Uthaymeen said: "Anyone who does not have a mind is not obligated, and no religious duty is incumbent upon them, neither prayer, nor fasting, nor feeding [the poor]; meaning, nothing whatsoever is obligatory upon them."