Wa `alaykum as-salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear brother in Islam, it gives us pleasure to receive your question and to see the Muslim youth are interested in knowing the teachings of Islam.
The Prophet (peace and blessings of Allah be upon him) taught us as Muslims many du`a’s (invocations) and guided us also to many verses in the Qur’an that one can recite to ask Allah for His help and favors. So, a good Muslim should usually read the Qur’an and make du`a’ to Allah to grant him or her blessings, health, etc.
Answering your question, Dr. Wael Shehab, PhD in Islamic Studies from Al-Azhar University and currently the Imam of the Downtown Toronto Masjid in Canada, states:
First of all, it should be clear that a Muslim should never lose hope in gaining Allah’s help and favors. So, you and your aunt should never despair of Allah’s mercy; He Almighty is able to grant her quick recovery. Moreover, Allah will reward her for her patience and satisfaction with Allah’s decree.
It is my advice, also, for her to check some reliable professional physicians, as a Muslim is recommended to seek medication and rely on Allah. Imam Ahmad reported that the Prophet (peace and blessings of Allah be upon him) said, “Seek medication, O slaves of Allah, for Allah has not caused any illness but provided a medicine for it except one illness; old age.” (Ahmad)
As for the ruqyah, it is not allowed to use a ruqyah (healing invocation) other than from the Qur’an and Prophet’s du`a’s.
So, you may teach her some Prophetic supplications or Qur’anic verses that imply seeking Allah’s favors and recovery. For instance, she, or you, may say the following Prophetic du`a’s:
“O Allah, Lord of mankind, I beg you to remove the suffering. I beg You, as You are the Healer, and there is no healing but Yours, to bring about the healing that leaves behind no ailment.”
“I seek refuge in Allah‘s perfect words from the evil of all what he has created, from all devils and insects and from all envious eyes.”
Also, the Prophet (peace and blessings of Allah be upon him) said, “If one has a pain, one should lay one’s hand on the painful spot and say: I seek refuge in Allah’s Dignity and Ability from the evil of what I am suffering and guarding against.” (Al-Hakim)
One, moreover, may read the last two chapters of the Qur’an (surat al-Falaq and surat an-Nas) three times every day and night. In addition, one may recite ayat al-Kursi (verse no. 255 of surat al-Baqarah)
May Allah accept your and our good deeds!
Allah Almighty knows best.