I was recently asked to post about assessing the impact of NGOs in Ghana. Here are some resources that I found:
Be sure to check out the Institutes, Think Tanks and Reports section of your course guide. It lists several websites that will have reports from major non-profits in West Africa.
In addition to the general social science article resources (e.g. JSTOR, ProQuest, Google Scholar, etc.) two databases that will have international NGO reports would be:
Search these databases for keywords like (NGO or non-governmental organization or intergovernmental organization) and (accountab* or monitor* or evaluat*). Here are links to two productive searches I ran in Google Scholar's Advanced Search screen: