Not everybody you meet and want to be friendly with is going to like you, and some are going to despise you. You asked her and she wouldn’t say. There is nothing you can do about it, so leave it alone. If you get an opportunity to change your apartment so that she is not a neighbor, you may want to do so, but don’t call any attention to the problem. Something about you triggers her coldness because it is in her upbringing or reminds her of something. There is nothing you can or should do about this except to minimize interactions with her and to always have someone else present when interacting. Her dislike of you is about her, not you.