welcome to the forum.
regarding your question: These were part of the old desert battledress uniform, so they were used atleast in theory during the DBDU time frame. let's say 1981 to 1991, when the desert uniform commonly known as Chocolate chip was replaced by the DCU (3 color desert camouflage uniform). Clearly the former were used until much more late, replacing a uniform and reissuing a different camouflage takes time.
there isn't headgear to go with it, the standard issued set was composed of parka, trousers, parka liner and trouser liner. The liners are the typical quilt ones, infact they are interchangeable with the m65 liners, but the night camo parka ones are longer (they have a different stock number).
Commercial uniforms, patrol caps, pasgt vest and helmet covers existed, but they are commercial.