Board Thread:General Discussion/@comment-2601:5CA:C303:E9F3:74A4:C5DE:F7F7:F0F5-20180517071720/@comment-25350022-20180517091510

I doubt she entered Geirmund's hall and escaped, because the entrance to the hall is a drop down into water, which you then find through some spiders before finally reaching the main chamber where the draugr are holed up.

But the rest of your theory is quite sound, although you may have given this too much thought.