Advice on what to say to a coworker who didn't get the job you ended up getting [same dept]?

I just got promoted to a new job in the admin dept where i work. There was another coworker who applied for the job and didn't get it. I will now be her boss... She sent me a e-card saying no hard feelings, and i want to send something back. But I really not sure what I should/shouldn't say.Advice on what to say to a coworker who didn't get the job you ended up getting [same dept]?
';If I could have picked someone it would have been you';Advice on what to say to a coworker who didn't get the job you ended up getting [same dept]?
ty for being a good team player. i look forward to working with you'





then cya and get her a promo or a transfer asap,
Make her feel better by giving her special assignments like fetching your coffee?
Nothing. Just do your job to best of your ability, because they will be waiting for you to f*** up.If it starts trouble, ignore it, you don't have time now.