Dispute between Tenants and I'm in the middle

[Tony Murphy]

I have a situation with two tenants (two single women) in an up/down duplex who are currently feuding. I originally told them to work it out themselves but I then foolishly allowed myself to get dragged into the middle and I’m not sure how to handle it at this point. They lived there in relative peace for almost 3yrs until the downstairs tenant’s sister screamed at the upstairs tenant for playing music too loudly one day two months ago. Since then, it’s been a constant back and forth. They’re both retired and don’t leave very often so they’re in house house almost 24/7. One makes a noise and the other bangs on the floor/ceiling and then it just escalates. So bad that they we’re screaming at each other and a police cruiser driving by stopped and got involved. I’m not there so I get two completely different stories from each tenant. One says the other is banging all day and one says the other is doing it. Neither is innocent and I’ve told them both multiple times that they need to act like adults and be respectful of the other (music and noise to a minimum during the day and nothing at night as stated in the leases.) Yesterday, the upstairs tenant actually tried to extend an olive branch by offering to help shovel snow and talk to the downstairs tenant about the situation. Downstairs tenant shot her down and said she had nothing to say to her (told me she sounded phony and not sincere) so at midnight the upstairs tenant supposedly started pounding on the floor for an hour, I guess in retaliation...

These two grown women are both acting like petty children and they expect me to be the parent. Both pay their rent on time and the house is in Massachusetts so evicting either could be a potential nightmare dragged out for god knows how long. What’s my next step?