I cannot even imagine how hard it would be to go through another pregnancy, having the fear of losing it in the end. That must have been so hard to deal with. It's good she got a healthy baby in the end, but I bet she still grieves over the baby she lost. That would be so difficult!
This happened to a friend of mine at 8 months. They had autopsied the baby and could not find a conclusive cause of death (it wasn't a cord issue). My friend and her husband had to go through some rather extensive testing because apparently there is something genetic from the parents that can cause this to happen with future pregnancies. Thankfully they did not have whatever markers they were looking for but I hope that your friend's doctor will do the same testing to rule out an inherited defect.
Incidentally, she recently gave birth to a healthy baby!
A cord problem is usually the reason for losing a full term baby. That's why they say that you should really keep a movement count daily. It's really the only way to know. I'm really sorry for your friends loss. It must be so hard to go through something like that. I can't imagine and I hope (knock on wood) that nothing happens with this or future pregnancies.
A friend of mine lost her baby almost full term - I believe the her cord wrapped around her neck. They realized it during a routine ultrasound.. and she had to deliver the baby as normal :(