Well the UN doesn't do fighting, peacekeepers are meant simply to keep the peace until another force arrives. So for fights, these forces are pointless. In the end in conflicts such as these the peacekeepers will become easy targets for Boko Haram.
The first and primary part of any counterinsurgency strategy is to contain the geographical area which the insurgency operates in. Boko Haram doing raids into neighbouring nations is nothing new, but the scale has increase. The neighbouring nations need support from other African countries, so the African Union, would be the best way of doing this. Not really the UN, or any western forces. From their the Nigerian forces are able enough to deal with Boko Haram. We just don't want it become a threat to other countries, or becoming some kind of civil war. The two go hand in hand I believe.