Been there..here are a few things I would send:
LL Bean or Land's End coat
LL Bean sells flannel lined blue jeans - best thing I did!
Thin, silk long underwear - not the thick ones
Good socks, good boots, gloves, hat, scarf
dress in layers, they keep the heat on high inside where you will roast. The heat is controlled centrally by the cities and you cannot adjust it!
Pack toilet paper, Antibacterial wipes, and hand sanitizer - trust me on this. I would also pack a few of those hand warmer packs, look for these at a hunting store or sports dept.
A money belt, preferrably the kind that hangs around your neck under your clothes.
I would not wait to shop there. Depending on the size of city he is going to can make a huge difference on what is available. Big cities like Moscow are very expensive. Once you get outside the biggest cities it is a very 3rd world country! PS. In mid-April they turn off the heat EVERYWHERE! When we were there they turned off the heat and it was still snowing outside. We had to go buy an electric heater for our hotel room..just nuts!