Translation:Are you going to be at your house tomorrow?
I believe "to stay" is estarse. Therefore it would have to be estarte or te estás.
If interested please see the link
Funny, that link redirects me to: https://www.thoughtco.com/agencias-americanas-que-contratan-au-pairs-1965349. LOL
I agree with Arthur and Jimmy. I also put this, was marked incorrect, and reported it. Saying "you are going to stay in your house tomorrow?" is often used as a half-question, as if the speaker already thinks that the person will stay in their house tomorrow. However, it depends on the tone of voice. The more inquisitive it sounds, the more the asker is less certain of the answer, and vice versa.
Yes, estar does mean to be. But, the phrasal future tense is formed by using conjugation of "ir" and adding "a" + verb infinitive. (Yo) Voy a estar = I am going to be (or Am I going to be?) (Tù) Vas a estar = You are going to be (or Are you going to be?) (Él) Va a nadar = He is going to swim (or Is he going to swim?) (Nosotros) Vamos a dormir = We are going to sleep (or Are we...) (Ellas) Van a correr = They are going to run (or Are they going...)
[If you scroll down on the main page, this set of lessons has an explanation of the phrasal future tense.]