The most powerful IED that could be transported by a recreational drone would be one carrying a model rocket engine. These contain PETN solid fuel, which is a high explosive. With clever design, this solid fuel engine could be used to make a small explosion. The problem? This would be at most enough to damage a few windows, and maybe maim somebody at point blank range.
What's "recreational" in this context?
The M18A1Claymore mine weighs under 4lbs and fires roughly seven hundred steel pellets like a shotgun. The proposed Amazon Prime Air drones could carry a bit over 5 lbs, so could easily mount a Claymore.