I had to earn that Best Selection Award because I felt my answer didn't solve your problem.
I think I might have found the Top Category for you. Massachusetts
Create a sub-category [[Category: Massachusetts Veterans Facilities]] under that to follow the standard naming convention for sub categories there. Then create the [[Category: Soldiers Home, Chelsea, Massachusetts]] under the Massachusetts Veterans Facilities category.
Since it is in and maintained by the State of Massachusetts for Mass. Veterans, you can't go wrong putting it there. And if a another Top Category that encompasses Veteran based program, facilities, etc, is found, you can still add this to it then.
I knew there had to be a place for it. There's always room for Jello on WikiTree. LOL