The obvious correct answer is " A" regardless of the personal satisfaction you might get from " B" . My reasoning is this, with " A" any link to a larger poaching operation than an individual has an opportunity to be stopped with some serious fines and or jail time. With the scenario you established, this is what is going on, " taking only the money parts" kind of lays the background for that.
My question is, is this a hypothetical question on your part or is it part of an actual incident? If it is part of an actual incident, discrete action on your part may only lead to continued poaching on the same or larger scale. Report them and let the State or Federal game people do their thing.