1. They don't always work, for a variety of reasons. Not least, sometimes they are left in the "Off" position. Other times the crash simply doesn't trigger the ELT.
2. Three people on the flight plan, three bodies found. So?
3. A 1900D is really just an up-sized King Air, only slightly too large to be called a "light aircraft." Here it was being operated just like any light aircraft, not like a Boeing 737 making an approach to Abuja or Lagos, say.
4. So?
5. You will find 5N-XXX markings on the rear fuselage or tail fin, close enough to be loosely termed the "tail."
6. So?
You seem to want to stir up doubt. From my experience of flying into bush strips in Nigeria in bad weather I have very little doubt that this was just another foreseeable accident, down to the inherent risks in this sort of operation. You want to get into Obudu in bad weather then this is what you may get. Or you can take a "mammy wagon" or wait three months for the end of the rainy season, your choice.
Ever flown into Benin City when it was rainy or dusty? Wanna bet the rules (Visual Flight Rules only there) were being bent or broken?