If you don't have a great relationship, she might assume you spit in them or worse. Lol.
Are your skids with her for Christmas? If so, I think that's a very nice gesture, and the kids will probably get to enjoy the goodies too.
You're not obligated to give her cookies. If you are expecting something wonderful to happen (a huge thank you, making peace at last, etc), I wouldn't do it b/c you'll likely be disappointed.
So basically, it's up to you.