Find the man with C4s and give his detonator to someone else. Keep everyone back except for the man who has the C4. Quickly run to the tank and plant the C4. When you are finished, get another troop to call him back. When he runs back, the tank should be focused on him. Change to the man with the detonator and use it. If this works, everyone should make it out alive. However, if he does not make it, you can clear the area then heal him.