I would appreciate it if you would answer the following questions:
1. Is there a physical road (i.e. asphalt or gravel, etc.) located in the easement? Or is there merely the easement itself with no road?
2. Where exactly is this grass you are referring to? Is it on the edge or slightly into the easement, or is it in the middle of the road?
3. Does the presence of the grass prevent people from driving to or otherwise accessing their parcel(s)?
No offense, but your post is poorly written and difficult to completely understand.
My assumption based upon what you have written is that the neighbors recently had new loam and seed or turf installed, possibly inside the easement. They appear to be attempting to protect it so it can have a chance to take hold. In this case, I would side with the neighbors on this one, since it appears the stakes are merely temporary. Planting grass can get expensive, so if it were me I'd have a big problem with people walking over it before it firmed up.
Easement law, especially in the case of private easements, can get tricky. More information is needed before I can comment on that, so I'd appreciate it if you could answer questions 1-3

