Nero Vision (in Nero 9 or later) using the “Make Movie” function. It’s their editing software. Load the VOB there. Drag it to the time line and then press export.
A 20 year old DVD? Sounds more like Video CD. But Nero can read lots of formats, so it might not matter. There is probably a free transcoder on the internet too that can do this. I only started using Nero cause it could transcode AVCHD files to HDV, something I had needed at the time for a work project. Once PPro could handle AVCHD, I stopped using Nero for anything other than VOB files