I would think that your not getting a response is in your favor. Now you no longer have to wonder as to why the company made you such a low-ball offer.
Remember, they are depending on getting newer guys with no experience in the region. That is the only way they can hold the cost down. Even if you only give them a year, it is still a year of not paying adequately for the conditions and security that exist in Nigeria.
If you go, make sure that your family is well covered by life insurance. Make sure that you have good health insurance and visit the CDC website and get all of the vaccinations that are recommended.
I hope that I am wrong, but I see things getting much worse over there before they get better. It is well within the range of probablility that one of "ours" becomes a hostage or worse within the next 6 months.
Be Careful over there...