I think she was cursed, she has supernatural powers that made her undead. A priest made a ritual to trap her in a coffin ordered by her pharaoh father because she can overthrow him from his throne that's what I understand in the previous chapters.
I thought she was surely her step-mother. So, there are cases, where the child brought from the past relationship won't receive kindness nor family love. Even more so, if the child is "special" in a way that isn't regarded as normal.
Is she a mummy? or she was still alive after 10 years in that coffin?
I think she was cursed, she has supernatural powers that made her undead. A priest made a ritual to trap her in a coffin ordered by her pharaoh father because she can overthrow him from his throne that's what I understand in the previous chapters.