Of course we can blame the Obama administration. The US chose not to put the BokoHoron monsters on the terror group list. When the first calls to intervene came out, Kerry's response was they needed the permission of the Nigerian government. Besides that, we have to wonder if their weapons are coming from all of the stuff we've given rebels in northern Africa, or from Libya's stash that hasn't been secured.
As I understand it the school was guarded but not well. 2 or 3 military guards who were easily taken out by superior numbers.
That said the Nigerian government is rife with corruption.