Before I mention any gear, I want to share a few weather resources. First, here's the NOAA Mountain Point Forecast and historical data for Mt Mansfield in Vermont. The records show you the average and record highs and low temps, along with some snow depth data.
Next, here's the historical data for the Mt Washington summit station. Again, you can get some very exact historical data - temps, wind speed, conditions, etc.
I use this NOAA page to keep an eye on snow depth.
I hope your friend has a generous budget. Winter gear isn't always cheap. Your friend will be spending a good deal of time in his shelter, so it should be one he likes. I'd check out the Marmot Aplinist tent, if the Hilleberg is out of his budget. A Black Diamond FirstLight could work too, but setup can be a little more difficult and no vestibule. Considering that he could get pinned down on a ridge, I'd want a fully enclosed shelter.
He should make sure to have a neoprene face mask, balaclava, neck gaiter, micro spikes, snowshoes, trekking poles with snow baskets, lithium batteries for the headlamp, water bottle cozy, duct tape for repairs, etc.