Wilhelm Kober & Co. Suhl was a hair clipper & knife maker, most famous for daggers of the nazi era (according to Darrin Weaver's Trademark book), they also made MG components, they were listed in Musgraves (German Machine Guns) & Goldsmith (Devils Paintbrush) as MG component suppliers, and during World War II they used the code "893" and later "ghh" and made MG34-42 barrel extensions (Ken Huddle).
Apparently the firm was of some importance or at least relevance, having been the first firm in Germany to make mechanical hair clippers beginning in 1889, they expanded their facility in 1900. The only pre-nazi era thing I have recorded for them is these muzzle covers for the Gewehr98, they are not uncommon to find marked to them, I have had a couple and seen several others. Finding maker marked muzzle covers is a good score, they are worth more imo.
The C/E is the same thing as a waffenamt, it is acceptance of the part or component, in this case it means acceptance of the muzzle cover by the military inspector (inspected under his authority). It probably dates to 1916 or after due to the Latin character, usually they used fraktur or Sütterlin script prior to 1916 for inspectors, but increasing after 1915 (usually mid-late 1916) some of the inspectors used regular letters.
Keep an eye out for others, I track these by maker (trademarks, logo etc..) and have a good database on them, but I am sure there are others!