At the end I think only dune 2000.exe it's 100% necesary to work, as any patch (besides the oficials 1.03 and 1.06 patches) done into the game I think it was done into this .exe itself.
I have a portable version that I use to mess when I am trying to use Tibed, new colors and so on, so I don't touch my gruntmods versions, and since it is portable I can do multiple copies or extract the .zip again withouth needing me to install or anything. So, for this portable version of the game I only copy the dune2000.exe, config.exe and the launcher. The config because game may not launch, or do it in a weird looking way, and the launcher because at the end of the day I am going to load my playground map with editions and personal tests, but if it was for playing the vanilla game the dune2000.exe could be enough.
The C&Cnet.exe will download more stuff like the online maps, I don't have this or execute into my portable version, so maybe it is not needed at all.
Here, on this post there are some instructions on how to install your game from the CD and the patching needed. It has listed the dune2000.exe and the config.exe, but it could be possible that even withouth the config the game works, just with default resolution but it depends on the computer and the graphical cards or something about that.
This post just assume you install from your CD version, so maybe it can help you to see exactly what amount of files are needed to make it work.