I was researching this for a friend and look back over my many years as a mother and a child carer. I can remember my things the children done to bring them comfort and most things involved bring held and hugs. Security blankets my son is 26 and still has the one he had when he was 5. It is well worn these days but still provides comfort.
I was thinking that you could design on with an angel on it and some nice prayers of comfort.