Is there a way to programmatically protect a password folder in Android?
By default, files stored in the internal storage are private for your application, and other applications cannot access them (and also cannot).
http://developer.android.com/guide/topics/data/data-storage.html#filesInternal
AFAIK, No, you cannot.
You can pin the contents of the folder and save it as a zip file with a password. This is the closest solution I can think of. Of course, the folder will no longer exist.