Here's a link to 5 healthy hot cocoa recipes that will give you alternatives to the commercial mixes you can buy in the grocery store, which usually have too much sugar. Homemade hot cocoa with milk or milk alternative has lots of calcium and cocoa has antioxidants.
Regarding coffee and bone density, general guidelines from the Osteoporosis Foundation suggest that coffee in moderation is fine, but drinking more than 3 cups a day could lead to poor absorption of calcium. Other caffeinated beverages such as black tea or soft drinks pose the same risk. Additionally, more than 2 alcoholic drinks a day could affect calcium absorption and weaken bones. So an occasional Irish coffee for dessert would not hurt - just don't overdo it.
As I mentioned in a previous post, miso broth packs a lot of nutrients and homemade chicken or beef broth made from meat with bones has calcium and other benefits. Last fall when I was on a clear liquid diet for a day, I tried hot apple juice diluted with water to cut down on the sugar. (One cup of apple juice has 26 grams of sugar.) I thought it was just as good as full-strength hot apple cider.
Happy sipping by the fire this winter!