There is nothing wrong with giving food and drink to a mentally impaired person during the day in Ramadan
Question

                On the first day of Ramadan, I had a visit from an old lady who is one hundred years old. Sometimes she is aware and sometimes she is not aware. She asked me to make coffee for her, and I did that and brought the coffee to her. Is there any sin on me for that? Please note that I told her that it was Ramadan. Please advise me, may Allah reward you.
Praise be to Allah.
      If it seems that she is mentally impaired and that she has 
      become senile, there is nothing wrong with your making coffee for her, 
      because she is not obliged to fast. The fact that she is partly rational, 
      such as when she says, ‘Do such and such or bring me such and such,’ does 
      not mean that she is of completely sound mind. In most cases one who 
      reaches the age of one hundred has become senile and has changed. If it 
      seems to you that she is mentally impaired and that she is not fully 
      aware, there is nothing wrong with her eating and drinking. But if you 
      think that she is fully of sound mind and that she is being negligent, 
      then do not give her coffee or anything else, lest you are helping her in 
      falsehood. Allah says (interpretation of the meaning):

    “Help you one another in Al‑Birr and At‑Taqwa (virtue, 
    righteousness and piety); but do not help one another in sin and 
    transgression”

    [al-Maa’idah 5:2].

    If a person asks for food in Ramadan and he is healthy and is 
    Muslim, he should not be given either food or drink or cigarettes, and he 
    should not be helped in falsehood. 

    But if he is mentally impaired, such as one who has an 
    intellectual disability, has become senile, is insane or is very old, there 
    is no blame on them because fasting is waived in their case. End quote. 

    Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allah have mercy on him)