If she dies as a person who rejected Islam, she will enter Hell, eternally.
And whoever of you reverts from his religion [to disbelief] and dies while he is a disbeliever - for those, their deeds have become worthless in this world and the Hereafter, and those are the companions of the Fire; they will abide therein eternally.
— Quran 2:217
She will be going to hell.
Allah says in the Qur'an, chapter 3 verses 18-19:
"Allah witnesses that there is no deity except Him, and [so do] the angels and those of knowledge - [that He is] maintaining [creation] in justice. There is no deity except Him, the Exalted in Might, the Wise. Indeed, the religion in the sight of Allah is Islam. And those who ...