DME is the shortest CW route, two different products offered - two A321 flights and a 777 flight.
RT in CW will set you back 68K for two seats, with your additional avios should be doable.

However, Moscow in January is not for those unkeen on cold weather, and you may need to factor in the the cost and time for a RF visa. That said, Moscow is a fascinating destination, with culture, sports, food, nightlife in spades.

Happy travels!