I see your lovely intentions, but please be cautious with food.
Food can also make people ill, and even if it was perfectly fine, people can blame you for it....you see?
Imagine she will miscarry again, what if you brought her food shortly before this, and she is thinking your food caused it?
You can never go wrong with beautiful scented flowers though. She will be delighted and it will do her good. You could also bring her a collection of uplifting short stories, poetry, soft relaxing music, a beautiful fan for her hand if it is hot, and other things that bring her comfort and joy.
Food is a great idea, but like I said, you could also bring yourself into a possibly vulnerable position, but then I don't know...perhaps some ripe, exquisite, organic fruit with lots of vitamins in it ? In a basket along with flowers and a nice CD or book?
(Don't know how your budget is....)
I'd be more than happy about this.