OK, I have some questions:
1. What operating system are you using to run c2 (windows / windows in wine or some other emulator)?
2. What operating system are you trying to run the nw.js exported project in?
3. Does your game preview in nw.js option from c2?
As far as I know, .dll files do not run on a mac, so it seems to me that you are trying to run nw.js export on windows, so the osx32 and osx64 folders (which contain mac exports) are not what you want. If you're on windows you need to try either the win32 or win64 folders.
If you're trying to run on osx then this forum question
will probably help.