The ruling on whoever is unable to fast due to old age or illness
Question :
If my mother became ill some days before Ramadhan, and the illness weakened her, and she is elderly, and she fasted 15 days of Ramadhan, but she is not able to fast what The Book of Fastin remains and she cannot make up for the days, is it correct for her to give charity? How much daily charity would be sufficient since I am taking care of her? Do I pay what is due on her in the situation that she does not have anything to give in charity?
Answer:
Whoever is unable to fast due to old age or an illness that the person is not expected to recover from, then that person breaks his fast and feeds a poor person for each day. Allâh said:
"And upon those who are able to do so, i.e., fast, but with difficulty, there is a ransom of feeding a poor person."
Ibn 'Abbas said: "This was revealed as a concession for the extremely old man and the extremely old woman who are not able to fast. Thus, they feed a poor person in place of each day." This was recorded by Al-Bukhari.
Therefore, your mother must feed a poor person for each day, and the amount is half a Sa' of the food of the land. If she cannot find anything to give as food for herself, then there is nothing due on her. If you want to give food on her behalf, then this is a form of doing charitable good and Allâh loves those who do good.
Source:
The Permanent Committee
Fatawa Islamiyah, Vol. 3 Page 282