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”
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)