Most mission agencies at least in the United States have a policy that they will not pay ransom for kidnapped staff. It is based on the premise that however we handle the situation, we cannot put other missionaries at risk by our actions. Paying ransom simply encourages terrorist groups to repeat their actions since it pays off. This is why Somalia terrorists keep hijacking ships in the Indian Ocean. They have learned from experience that the companies will settle and it becomes a money making enterprise.
Mission agencies do have resources at their disposal for the negotiation or rescue of kidnapped staff. These are highly trained professionals who come out of the security world. If handled well, there is a very high probability of a positive outcome for kidnapped staff. Of course, groups like ISIS may change that equation as their ruthlessness is second to none. Good agencies have well thought out plans for crisis situations and update those plans regularly as threats emerge.
In today's world it is critical that we pray for the safety of our missionaries and national partners. It is an increasingly unsafe world where the tentacles of evil can reach almost anywhere. That is not to say we should live in fear but it is to say that we should pray for God's protection.