OkadaBooks

Here is a list of National Essay Contests in Nigeria:
The Nigerian Stock Exchange (NSE) 2016 Essay Competition
http://www.nse.com.ng/mediacenter/pressreleases/Pages/NSE-Opens-2016-Essay-Competition-to-Promote-Financial-Literacy.aspx44

2017 Senior Secondary School Essay Competition for Schools in Abuja

https://nigerianscholars.com/2016/10/2017-senior-secondary-school-essay-competition-schools-abuja.html

Ecobank National Essay Competition for Children 2016
http://www.vanguardngr.com/2011/05/ecobank-to-reward-children-with-mega-prizes/