While doing a low level mission (roving rogue drones lvl 1), I used a fast frigate to do the mission, I needed to go AFK so I aligned to a station and let it fly off with afterburner going, well that AFK lasted longer than expected, got back and was about 1800km out from beginning, the drones, about 1500km from beginning.
So used my alt to come in and 2 drones insta warp to him from over 1000km out, just like the new gala event rats, so be warned, they warp to you in missions.
MJD is the key module for such fits, IMHO. And 100 km distance it gives will not let rats warp to him. So if you keep operating between 100 and 150 km you are still safe.
Npc’s do not obey the same rules as players. We cannot warp inside a deadspace, npc’s can and do. There is nothing to stop them doing under 100km warps, but I suspect what they will actually do is warp 500km to a ping then back to you.