Your folder should contain, for each offline character (replacing here the character’s name with “X”) :
X.ctl
X.d2s
X.key
X.map
X.ma0
X.ma1 (only if you’ve reset the map by changing act or through the method explained to you at least once)
X.ma2 (only if you’ve reset the map twice)
X.ma3 (only if you’ve reset the map three times)
Note that you can delete the 4 map files without risk (the most recently modified one is your current map layout, so if you delete it, the game will generate a new layout, if I recall properly).
The folder also contains, for each multiplayer character, where Y is a seemingly random number :
XY.ctlo or X.ctlo (or both).
XY.keyo or X.keyo (or both).
I think those files will be created again if you delete them.
Finally, there are a few other files :
Custom.key (I guess this is your custom key binding setup)
Settings.json (that should be your game settings)
SharedStashHardCoreV2.d2i
SharedStashSoftCoreV2.d2i (these files are the contents of the shared stash tabs)
I encourage you to backup your folder before attempting any file manipulation.
The folder name is coherent with mine, too.