A) UN Peacekeepers will not attack the local militants, provided that the militants behave themselves. The militants will not make trouble if the UN peacekeepers dont attack. Therefore, UN peacekeepers will not attack the local militants, and the militants will not make trouble.
B) Either there is evidence that women of supernatural power (ie witches) exist, or there is no such evidence. If there is no such evidence, then we have no reason to believe in witches. If there is evidence, we do have reason to believe in witches. There is no such evidence. Therefore we have no reasons to believe in witches.
C) Either the herbal remedy alleviated the symptoms, or the placebo effect alleviated the symptoms. If the placebo effect is responsible for easing the symptoms, then the herbal remedy is worthless. The herbal remedy alleviated the symptoms. So the herbal remedy is not worthless.