This is how to conjugate the verb ESTAR (which means to be) in the present tense:
yo estoy, tu estás, el/ella/Usted está, nosotros estamos, vosotros estáis, ellos/ellas/Ustedes están.
Your sentence is I am home. In Spanish, the word YO stands for I in English. This means that you would use the form estoy in your example.
The correct answer is B. estoy.
esta would be the right way to say it
What is the theme to be developed? Hope this helps :)
