All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
No doubt evil eyes are true as the Prophet informed. Sometimes a person may harm one of his loved ones by an evil eye. However, as long as the enquiring sister was repeating “Maashaa Allaah” then she could not have harmed her niece. Muslim scholars have mentioned that saying “Maashaa Allaah” blocks the evil eye. They deduced this ruling from the verse (which means): {And why did you, when you entered your garden, not say, What Allaah willed [has occurred]; there is no power except in Allaah’?} [Quran 18:39]. Imaam Jassaas clearly stated that.
We ask Allaah to reward all of you for the trial that you are suffering from by loosing that girl. For more details refer to Fatwa 84035.
Allaah Knows best.