Tell her that prophet never practiced such thing. Instead The Prophet Muhammad (ﷺ) Said:
"In his Khutbah the Messenger of Allah (ﷺ) used to praise Allah as He
deserves to be praised, then he would say: 'Whomsoever Allah (SWT)
guides, none can lead him astray, and whomsoever Allah sends astray,
none can guide. The truest of word is the Book of Allah and best of
guidance is the guidance of Muhammad. The worst of things are those
that are newly invented; every newly-invented thing is an innovation
and every innovation is going astray, and every going astray is in the
Fire.....'
Grade : Sahih (Darussalam)
Reference : Sunan an-Nasa'i 1578
In-book reference : Book 19, Hadith 23
English translation : Vol. 2, Book 19, Hadith 1579
There are many authentic Dua for protection against evil eye. This is one of them:
It was narrated that Ibn ‘Abbas said: “The Prophet (ﷺ) used to seek
refuge for Hasan and Husain and say: A’udhu bi kalimatil-lahil-
tammati, min kulli shaitanin wa hammah, wa min kulli ‘aynin lammah (I
seek refuge for you both in the Perfect Words of Allah, from every
devil and every poisonous reptile, and from every evil eye).’ And he
would say: ‘Thus Ibrahim used to seek refuge with Allah for Isma’il
and Ishaq,’ or he said: ‘for Isma’il and Ya’qub.’”
حَدَّثَنَا مُحَمَّدُ بْنُ سُلَيْمَانَ بْنِ هِشَامٍ الْبَغْدَادِيُّ،
حَدَّثَنَا وَكِيعٌ، ح وَحَدَّثَنَا أَبُو بَكْرِ بْنُ خَلاَّدٍ
الْبَاهِلِيُّ، حَدَّثَنَا أَبُو عَامِرٍ، قَالاَ حَدَّثَنَا سُفْيَانُ،
عَنْ مَنْصُورٍ، عَنْ مِنْهَالٍ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ
عَبَّاسٍ، قَالَ كَانَ النَّبِيُّ ـ صلى الله عليه وسلم ـ يُعَوِّذُ
الْحَسَنَ وَالْحُسَيْنَ يَقُولُ " أَعُوذُ بِكَلِمَاتِ اللَّهِ
التَّامَّةِ مِنْ كُلِّ شَيْطَانٍ وَهَامَّةٍ وَمِنْ كُلِّ عَيْنٍ
لاَمَّةٍ " . قَالَ " وَكَانَ أَبُونَا إِبْرَاهِيمُ يَعُوِّذُ
بِهَا إِسْمَاعِيلَ وَإِسْحَاقَ " . أَوْ قَالَ " إِسْمَاعِيلَ
وَيَعْقُوبَ " . وَهَذَا حَدِيثُ وَكِيعٍ .
Grade : Sahih (Darussalam)
English reference : Vol. 4, Book 31, Hadith 3525
Arabic reference : Book 31, Hadith 3654
Also You can Recite Surat Al-Falaq and Surat An-Nas
Abu Sa'id Al-Khudri (May Allah be pleased with him) reported: The
Messenger of Allah (ﷺ) used to seek protection against the evil of
jinn and the evil eyes till Surat Al-Falaq and Surat An-Nas were
revealed. After they were revealed, he took to them for seeking
Allah's protection and left everything besides them.
[At- Tirmidhi].
Sunnah.com reference: Book 8, Hadith 25
Arabic/English book reference : Book 8, Hadith 1015