So I apparently started the Sanguine quest while Countess Caro was in Chorrol. Now she won't come back to her castle, but her guests are sitting there. I tried the "placeatme" cheat to make a clone of her show up, but it keeps telling me the spell didn't work, and I can't go on to the Hermaeus Mora quest without actually completing this. I had typed in the completequest cheat too, and it gave me a message saying I failed and the quest was done, but it still won't let me start Mora's quest.

I am playing this on the PC.

Have you tried waiting for a few days (or even a full week) ?
She should eventually come back from traveling.

That's the problem. I've gone off and done other things and checked back. She never shows up again.