Answer:
I believe that the answer is Usted.
Explanation:
The sentence is a command and therefore could go either way.
1. Yo espero que tú hables español.
2. Espero regresar temprano.
3. Pienso queesun buen hombre.
4. No creo quevengatemprano.
5. Es nesesario quevuelvaspronto.
<em><u>Nunca</u></em> seems like it fits in the blank.