Hi @Monish Lillaney, congrats on the soon to be new investment property. I'm not an attorney, so I don't have any legal advise per se, but it sounds like you've done what you can to get them to vacate. You've got an attorney representing you on the closing side who should be well versed in this area, your best bet would be to lean on him/her for guidance.
My question is, why are you choosing to close on 1/31 and not 2/3? If you inherit tenants and they choose not to vacate once you own the property, getting them out falls back on you. As you likely know, evictions in Massachusetts can be costly and time consuming for the landlord. This could range in the $5k-$10k range, per unit. The other option to avoid the eviction route, would be to offer cash for keys, which is still a costly route but can be done relatively quickly.
My recommendation at this point would be to push close date to the next week and do your final walkthrough the morning of closing, that way you'll know with certainty if these tenants are still there or they've vacated.
Good luck!