I also went through this and I have to say everyone deals with this experience or any grief situation differently. What is great for one mom is not good at all for another. I can only speak of my reaction and how I would have wanted to have others react to the situation. This is not necessarily how anyone else would. I "miscarried" (they still call it a miscarriage at 3-4 months and will not stop the late onset at all, usually they try to help it along if its already looking bad) on February 27th of this year and it was very devastating for me. My husband did not know how to deal with it and he really felt bad but didn't know how to react that well. Emotionally he was not feeling the loss I did so that was a little hard for me to deal with. When I lost the baby I never saw it because it fell into the toilet (I felt it coming out so ran to the bathroom) and all I could see was an ocean of blood. I just stood there and cried and cried. I called my midwife back to confirm I lost the baby and then also called my aunt whom I had confided in that I was pregnant (I had been showing a bit but covered it with a lot of loose clothes) and who knew I was experiencing this situation. She told me she had had a similiar experience and that no one but her husband had known about it too. That was reassuring. Also, I had to go in the following day to my midwife and the hospital and I cried like a baby. But...after that week of "mourning" the loss I decided it was part of a greater plan and I would get pregnant again soon. Sure enough I was pregnant by the end of that month and never looked back. I know it was truly truly a blessing to get pregnant right away afterwards and I thank G-d every second of every day. The reason why I share my story is to let you know that whether I would get pregnant then or much later I decided that I did not want anyone else knowing about it or talking about it. I just wanted to close that chapter. It was painful but it was over. In my mind, it was my child but it also was not a formed child and it was not meant to enter this world. Losing a child that early in the process is just not the same to me as G-d forbid really losing a child. i have had a very hard time dealing with death in the past but for some reason I just had the attitude of "it is time to move on and get over it." That doesn't work for everyone.
In regard to how to deal with her anguish, I would just lay low. If you want give her a card with some meaningful words or maybe just leave her a message saying, "I'm here for you if you need me but I don't want to push you either way."
Good luck with dealing with them and hope they are blessed with another child in the right time. She should hang in there - it'll be okay.