Go search the archive and you will find the answer. But well, here is the summary:
Yes, 95 C280 does have a ventilation microfilter. The replacement interval is 45,000 miles/2 years based on the service booklet (you should have it with your car). The later C class uses a charcoal mictofilter that fits in your car as well. According to M.B.Doc, it lasts twice as long. And yes, PartsShop has it (part #210 830 08 18).
You can read the thread "94 C280 Charcoal Filter: Where is it?" for detail.
Harry (94 C280)