For this case we can translate the sentence as:
Juanito's father demands that his son __________ his homework with excellence.
We must complete the sentence with the verb "to do" in the present and third person. That is to say: El haga
Thus, the sentence looks like:
Juanito's dad demands that his son do his homework with excellence.
Answer:
Option B
El papá de Juanito exige que su hijo haga sus tareas con excelencia.
I know for sure that its wrong, but sorry im not sure how to fix it.
The answer would be C. la que
Es is for other reasons and está is for location