Praise be to Allah, the Lord of the Worlds.
Allah the Almighty has prescribed rules that preserve self and spare it harm. He commanded people to do whatever preserves self and avoid whatever causes it to perish. He the Exalted says," And kill not yourselves. Surely God is ever Merciful to you."{An-Nisa`,29}.
Therefore, Allah permitted the sick person who is unable to fast during Ramadan to break his fast. He the Almighty says," and if any of you be sick, or be on a journey, then a number of other days."{Al-Baqarah, 184}. If his fasting could cause him to die or face intense hardship, then he is obliged to break it. Al-Shirbini(May Allah have mercy on him) said, " He is obliged to break his fast if he feared that he could die, as stated by Ghazali whose opinion Al-Athro`ee regarded obligatory."{Moghni Al-Mohtajj, 2/169}. In case the sick person did fast while in that condition, his fast is valid, but he incurs sin if he was aware that fasting would cause him great harm.
We recommend that your mother make use of the above permission and avoid fasting, along with paying a ransom against each day in which she broke her fast. We also recommend that she multiply her other good deeds, such as night prayers, supplication, reciting the Quran and the like for she can bear to do these. Allah the Almighty says," God charges no soul save to its capacity"{Al-Baqarah, 286}. And Allah the Almighty knows best.