Based on what you said in your posting I would recommend calling elder protective services in Hull. You can contact them at 197 Samoset Ave # A Hull, MA 02045 and by phone (781) 925-0012.
If your roomate pulls a knife again call the police at 911.
The state sanitary code at 105 CMR 410.551 covers this
410.551: Screens for Windows
The owner shall provide screens for all windows designed to be opened on the first four floors
opening directly to the outside from any dwelling unit or room unit provided, that in an
owner-occupied unit, the owner need provide screens for only those windows used for ventilation.
All new or replacement screens shall be of not less than 16 mesh per square inch.
(1) shall cover that...
The answer to this question will depend on several details that are not in the question, so I can't give you a simple yes/no reply.
The best thing I can recommend is that the grandparents contact their local legal services office. There is coverage for every county in the U.S. and in Massachusetts you can find the office that covers your area by checking here http://www.masslegalservices.org/directory
The Grandparents will qualify for no cost legal help due to their income. And legal...
You likely have a good defense to this case and you need to make sure you file your Answer and Discovery on time.
You should call the Legal Services provider that covers your area for free legal assistance.
New Bedford is covered by:
Justice Center of Southeast Massachusetts LLC
231 Main St.
Brockton, MA 02301
you can also check http://www.bostonevictionlaw.com/ for some basic info and a link to the Answer form
In short you are likely to have several good claims against your landlord you should talk to an attorney for more detail. I'd be happy to talk to you or look for a lawyer who lives in your town that you trust.
Yes the landlord is usually responsible for most maintence. Call the landlord or send a note listing the items to be addressed. If that fails the city of boston can do an inspection and notify the landlord. But that should not be your first step.