My granddaughter has turned to witchcraft and away from God. When she was little she asked the Lord to come into her life. I know her name is in the Book of Life, but will she be with us when the Lord comes back for us?
Having one's name in the Book of Life is not a guarantee that your name will remain there. Names can be blotted out. "And the LORD said to Moses, 'Whoever has sinned against Me, I will blot him out of My book'" (Exodus 32:33). I cannot predict whether your granddaughter will turn from her sins or not. "He who overcomes shall be clothed in white garments, and I will not blot out his name from the Book of Life; but I will confess his name before My Father and before His angels" (Revelation 3:5). But witchcraft and sorcery will not get a person to heaven. "But the cowardly, unbelieving, abominable, murderers, sexually immoral, sorcerers, idolaters, and all liars shall have their part in the lake which burns with fire and brimstone, which is the second death" (Revelation 21:8).
It needs to be noted as well that there is no passage in the New Testament instructing people to ask the Lord to come into one's life in order to be saved. Instead, we find, "Jesus answered and said to him, "If anyone loves Me, he will keep My word; and My Father will love him, and We will come to him and make Our home with him. He who does not love Me does not keep My words; and the word which you hear is not Mine but the Father's who sent Me" (John 14:23-24). Such keeping of the commandments of Jesus would include the instructions on what we must do to be saved. More details of this can be found in "Things That Accompany Salvation."