So menu library itself is essentially another app that can be used by other apps and your app. App folders and project folders are usually in the same folder. Here is one layout you can use.
MyApp/MyApp/Template/...
MyApp/App1/...
MyApp/App2/...
MyApp/Menu/...
or it could be under MyApp where view.py contains your Menu code.
MyApp/MyApp/view.py/...
MyApp/MyApp/Template/...
MyApp/App1/...
MyApp/App2/...