My question involves landlord-tenant law in the State of: Massachusetts

Hi y'all!

I'm visiting Massachusetts and writing in for a friend as I already have my account.
Here's the skinny:

- landlord lives above apt.
- my friend moved in w/ her original tenant who had discussed this at length with her. Unfortunately this was an oral agreement between landlord and original occupant. This convo took place in Jan 2013.
- my friend has lived here quietly and happily til this week when original occupant went on holiday and my friend had me and another friend up for a visit.
-this ENTIRE week landlord has been knocking on the door. She repeatedly asks us who we are, who my friend (her rent paying tenant) is and accuses him of moving us all in. i live in FL currently. I am NOT living here! i have a plane ticket! a suitcase! She will harangue us for 30 minutes and then go back up, only to come down 10 minutes later and beat on the door again. Wash, rinse, repeat. It's maddening, I'm sorry.
-the town we are in is Watertown and tonight during the lockdown she went OUTSIDE and was wandering about. Friend darted out to try and coax her back upstairs (we all have grandmothers) but it took a cop to do it. She yelled at the officer.

I don't know WHAT to tell him to do. I don't think she has the mental capacity to evict him as a sublease (she agreed to) and original tenant cannot pay alone.

She is, however, driving and operating a gas stove up there, as well as harassing us /him every chance she gets.

I don't mean to sound unfeeling in this post.

HELP!