I only have one suggestion to make and that is
TeHN (The e-Helpers Network).
You can Google it
It is the most trustworthy Nigerian charity organisation that I know that is not dubious and is run by credible individuals and I can vouch for them.
They carry out charitable activities like paying for hospital bills for the sick, paying for surgery operations, education etc.
Even as Nigeria experiences the Boko Haram crises they still donate to the internally displaced people too.
Although there are other charity organisations, like I said, I don't really trust them.