All praise is due to Allah, and may peace and blessings be upon the Messenger of Allah.
Being illiterate or advanced in age does not exempt a person from learning the rulings of prayer that they are capable of learning. Therefore, she should be helped gently and patiently to learn what she needs.
Reciting Surah Al-Fatihah is obligatory in prayer, whereas reciting another surah afterward is Sunnah. If she cannot memorize another surah, there is no blame upon her.
While prostrating, she should say, “Subhana Rabbiyal-A‘la” (“Glory be to my Lord, the Most High”) once, although repeating it three times is preferable. She should be taught as many prescribed remembrances as she can manage. If she is genuinely unable to perform or say something, then what is beyond her ability is waived, and she should perform the prayer and recite the remembrances to the best of her ability.
The Sunnah indicates that obligations are waived when a person is genuinely unable to fulfill them, and that religious duties are determined according to one's ability.
Belief in resurrection and the reckoning after death is one of the fundamental principles of faith. It is established by the Qur’an, the Sunnah, reason, and innate human disposition. Allah, the Exalted, says:
“Those who disbelieve claim that they will never be resurrected. Say, ‘Yes indeed, by my Lord, you will surely be resurrected, and then you will surely be informed of what you did.’” [Qur’an 64:7]
Allah, Glorified be He, also says:
“He presents an argument against Us and forgets his own creation. He says, ‘Who will give life to bones when they have crumbled away?’ Say, ‘He will give them life who produced them the first time.’” [Qur’an 36:78–79]
Doubting the resurrection after the truth has been clearly explained and understood is an extremely serious matter. However, one should not rush to declare a particular person a disbeliever before understanding their circumstances, how much they comprehend, and whether the religious evidence has been adequately conveyed to them. This is especially important when the person is elderly, has received little education, and struggles to understand complex matters.
Therefore, she should be treated with kindness and patience, and the reality of resurrection should be explained to her in simple terms. It should be made clear that Allah created human beings the first time, and the One who was able to create them initially is certainly able to bring them back to life after death.
It is also advisable to remind her that Allah, the Exalted, is All-Wise and Just. In His sight, the obedient believer is not equal to the corrupt person or the disbeliever. This worldly life is not the end; rather, there will be resurrection, reckoning, and recompense.
Allah, the Exalted, says:
“Did you think that We created you in vain and that you would not be returned to Us? Exalted is Allah, the True King!” [Qur’an 23:115–116]
Seek the help of family members and relatives whom your mother trusts to teach her and help her understand, while frequently supplicating to Allah to guide her and improve her circumstances.
And Allah Almighty knows best.