Answer: Espero que mis hermanos limpien el baño.
In Spanish, there are three verbal moods: the indicative, the imperative and the subjunctive.
The subjunctive mood is usually used in sentences to express desires, hope, orders, emotion, possibility, judgment, opinion, necessity, or statements that are contrary to facts in the actualities, it is also called the mode of unreality.
That is, the subjunctive expresses uncertainties, subjectivities and possibilities and is presented as a possible, probable or hypothetical event.
In this context, the only sentence that uses a verb in subjunctive mood is:
Espero que mis hermanos limpien el baño
I hope my brothers clean the bathroom.
Note the spanish verb limpiar (to clean) conjugated in present (indicative mood) with the 3rd person in plural ellos (they), which are mis hermanos (my brothers) is limpian (they clean).
Nevertheless, if we use the same present tense in subjunctive mood, the verb changes to limpien, to express the desire or the hope of this person for the posibility the brothers clean the bathroom. In other words, this is a probable event.