This is a simple Javascript Library which would ease you when building the Address part of the form while you are targeting Nepali users.
Using the library is very easy. Just include the js file in every of your page and have the three select field with the ids as "developmentRegions", "Zones", "District" and "municipalities" (Now supports VDC's too). Check the demo for a preview.
The library needs lots of work done. I am more than happy to accept contribution.
Addition of Nepali Language Support
WTFPL