Based on my experience in this area, it is not the words that are said that helps heal the deep hurt the grieving are feeling.
It is the actions of love and service that are shown. Just sending the card will remind your friend that you love her, which will help her in her grieving process. No one has any magic words that take your friend's pain away.
I would encourage you to sign your name to the card and mail it. She will know you are thinking of about her in one of the hardest times in her life.
Callie Gordon is twenty-something, Lillie-Beth Brinkman is in her 40s, and social columnist Helen Ford Wallace is 60-plus. You'll also find a guest answer. To ask an etiquette question, email firstname.lastname@example.org. For more 20-40-60 etiquette, go to blog.newsok.com/partiesextra.