It would be best to go back to the original dvd and start over. Rip to the hard drive with DVDFab HD Decrypter and work with it from there. Or if the protection isn’t advanced, you could rip and compress with Shrink straight from the disk.
If you insist on using this existing file, you can rename the vob file with an mpeg extension (or use Vob2Mpeg), then import it into a dvd authoring program to get back to dvd-video with .bup and .ifo files.
DVDStyler is a free authoring program that should be able to produce a dvd-video for you.
At 2gb, the video should easily fit onto a dvdr…but that is awfully small for a full movie. Are you sure you have the whole thing? IMDB shows the run time as 110 minutes, or 96 minutes for the cut version. Either of those should be more than 2gb at normal bitrates for dvd movies.