The MBTA has free service tonight (yes that includes Commuter Rail from and to Providence), and special services after midnight.
Meanwhile RIPTA is detouring buses all over creation, not free, and does not run until or past midnight to most (any?) areas. So that’s not really a transit option if you plan to ring in the new year without your car.
So drive-walk-bicycle-hop-pogo-ski-sled safe tonight!
Update: A DC area charity is providing free cab rides to anyone in Washington too drunk to get home tonight. Crazy, right!?