On second thought, the place on Hampshire St. is not that close to the T. You could walk it, but you probably would not want to. (It's near The B Side, so if you decide to go
there, get a cab.)
A Cambridge House sounds like it might be a good bet. Or
Atrium House, but that might be a bit of a walk to the T as well. Or maybe
Newbury House which is bigger than you are looking for, but it's right smack on Newbury St. so you'll be sure to not miss anything.
Here's a list of some options around the place.