I mean no disrespect, but if your husband is not good at walking far, why is he visiting colleges.
A lot of good advice here. BU and Northeastern can be seen back to back. There is a 3 star La Quinta in Assembly Square Somerville, walking distance to the new Assembly Stop on the Orange Line so you would be able to get into Northeastern and BU that way. It’s also a short Uber over to Tufts from there too.