It explicitly states that in The Bible, Mary was a virgin who gave birth to Jesus because of God. She was planning on marrying Joseph, which means that she can not be God's wife. though in some way Jesus is God, it is different. You may recall The Father(God), The Son(Jesus), and The Holy Spirit. these three talk to each other sometimes. We also see that sometimes they reference specific ones instead of just God, so this means Mary can't be the grandmother of God or the Mother of God. She is the mother of Jesus. I'm sorry if this seems rude.