A. 

1. As it has already been mentioned, the bleeding was due to separation of the placenta. It is sometimes associated with high blood pressure, trauma (like fall, blow on stomach, car accident etc), a small fibroid in the uterus, too much water in the womb (polyhydramnios) and in many instances without any reason.
2. If the area of separation is too big, it can lead to fetal distress and even death of baby (even before it is born). Sometimes, this condition can be life threatening to the mother also.
3. Sometimes the cord wraps around the baby's neck only later (may not have been there before the scans).
4. It is difficult to comment in retrospect whether the baby would have survived with C-section. The gynaecologist takes a decision for or against a C-section taking several factors into consideration - difficult and unethical for someone not present at the time and place of emergency to comment.

I suggest you should look forward and try and get over this. I know it is easy for me to say this, but it does not help thinking over what has happened, isn't it? Also, you should be a pillar of support for your wife who is probably suffering a lot after this. Avoid a pregnancy for at least another 1 year. Ensure your wife takes good vitamin supplements. Taking folic acid and antioxidants is said to prevent recurrence. Be under the care of an experienced gynaecologist next time, and register for delivery in a tertiary hospital with good NICU facilities.