What are you referring to? You are mixing the semantics a bit and that makes it harder to answer your question. A freewheel hub will work with a 5 speed freewheel. People will put a single speed freewheel on a 120 freewheel hub.
A track hub will have a different size threaded area. When people say they
have a Single Speed bike they usually are referring to a single speed freewheel
on a freewheel hub. If they say they have a Fixed Gear they are usually referring
to fixed gear on a track hub - this won't work with a 5 speed freewheel.