[user104658]

Originally Posted by Nicky91

cause Sansa said she has hundreds of guards protecting her

she simply doesn't need Brienne that much

I don't think Arya would have any trouble with bog standard Winter fell guards though . Then again, while it would be a tough one on one fight with Brienne... Unless Sansa was glued to Brienne's side 24/7 then Arya would have no trouble getting past her either.

However I don't think there will be an Arya / Sansa confrontation anyway, I think both will confront Littlefinger. My guess would be either both confronting him and him fleeing Winterfell and getting away, OR Sansa confronts him but lets him leave Winterfell, then Arya takes him out before he gets far.