Yes, hair dryers were provided. Go, enjoy and do not worry about your hair.
I don't believe there was a hairdryer in the room. But there could have been a fitted one in the bathroom. It was very hot when we were there so drying my hair was not that necessary. Drop the reception an email. The staff are extraordinary at the Rainbow Hotel. You are going to have an extrordinary holiday... very jealous.
Get an answer from Rainbow Hotel Victoria Falls staff and past guests.