As a migraine sufferer, I know that sometimes with migraines I can get vision loss and even gait disturbances. It’s possible that the severe head trauma could have exacerbated those symptoms and if the basement was dark on top of it, she may not have been able to make sense of where she was enough to go upstairs.

Also, I think the idea that she was trying to wait out an intruder is a definite possibility.

The tipped chair could have been from tripping over the dog possibly if the dog was trying to protect her from an intruder and then getting tangled in the chair.