Reference: Fataawa Ramadhaan – Volume 1, Page 244, Fatwa No.193
Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-`Ilmiyyah wal-Iftaa. – Fatwa No.13008
Question: My mother is between 85 and 90 years of age, and has been afflicted with hemiplegia of the left side along with high blood pressure, diabetes and a heart condition. All this is based upon the doctor’s report. More than a year has passed, and half of the time she has spent in the hospital and the other half at home until she died. Bearing in mind that she would lose her memory at times, and would frequently ask questions repeatedly and call out [the names of] people who have long since passed away, such as her brothers. I do not know whether this is due to her sickness or old age.
The point for which I seek clarification is that the blessed month of Ramadhaan passed my mother in 1409 AH whilst she was in the aforementioned condition; Are her missed days of fasting required to be made up? If so, then is one of her children required to fast on her behalf or all of them? Or those upon whom fasting is obligatory? Or do we divide up [the fasting days] between ourselves? And must we pay sadaqah on her behalf, and if so, what is best – from her wealth or her children’s, bearing in mind she has many children both male and female? And what is the required amount of sadaqah specified for each day of Ramadhaan? And what type is it? And what is the method of distributing it?
Response: If the situation is as the questioner has stated, then there is nothing required of her [in terms of her religious obligations] due to her mental derangement. With that, it is understood you are not required to fast on her behalf, nor pay any compensation.
And with Allaah lies all the success, and may Allaah send prayers and salutations upon our Prophet Muhammad ﷺ and his family and his companions.