The Rebbe acknowledges the letter, hopes Chanukah was well, and shares a lesson from the Baal Shem Tov—always adding light, even in darkness, recognizing Hashem as King. He blesses the recipient with health and joy and sends regards to Mrs. Kovan and their son.
https://www.torahrecordings.com/rebbe/igroskodesh/014/004/5018