pixel_player9805316 Mrs. Claus and the Elves each have 9 sets of contracts. Each set has 3 contracts. For each set of contracts, you get the choice to complete contracts for Mrs. Claus (giving you crew tokens) or the Elves (giving you cargo tokens). You CANNOT fully upgrade both crew and cargo, so you need to choose wisely.
You're obviously doing a set for the Elves right now, which is why you don't see Mrs. Claus. But if you do want to upgrade the crew for your Rudolph at all, you will need to make sure you choose a Mrs. Claus set of contracts at some point. How you choose to upgrade your ship is completely up to you.
Also, when you choose between Mrs. Claus or the Elves, that choice shows up in the same popup screen. So if you've seen the choice for the Elves, then you've seen Mrs. Claus. You just didn't click on her set of contracts.