Well not knowing if this request is for the person asking or for someone else that they are asking for, or if its for them and the opposite sex , I would just point out.

Mens is located to the right, ladies located to left and leave it as that, unless you have a "family" restroom then I would say and our family restroom is upstairs..or to break the uneasy feeling of NOT knowing if this person is male or female you could do the left and right and then say , sorry we don't have a "family" restroom.