You're both right. I immediately thought of female nurse, but of course there are male nurses too.
This English sentence "The nurse sleeps in the ambulance." can be translated in two ways in Romanian, as Ser229339 says: "Asistentul (male) doarme în ambulanță." or "Asistenta (female) doarme în ambulanță.", both of them absolutely correct. You must keep in your mind that in Romanian the nouns are accorded with the gender.