As someone who was born and raised in NH and now lives in Melrose MA and works in South End I’d recommend hoping on Orange Line at Oak Grove (parking there is MUCH easier post pandemic) or drive down to Station Landing garage and grab train from Wellington. You could also get on red line at Alewife. If you’d rather drive in you could use Spot Hero app to book a spot in a garage near your meeting which will cost less than paying the garage directly.