Just check your Defs folder, generally you will have the latest VPS version plus the previous one, these contain the full uncompressed (speeds access/scanning) virus definitions database, this is currently approx 70MB, so two of those would be 140MB.
On occasion you may see 3 versions there, but that should be cleaned out by the avast housekeeping.
In the greater scheme of things the whole avast folder is only 250MB (on mine also) a drop in the ocean with the mega-gigabyte drives. So if yours is 250MB then it looks like you have just two VPS sub-folders in the defs folder.