NPC Spawning another NPC

[chrismed0]

You will have to forgive me if I ask about some of these quest scripts. I can do basic quests but I have to ask about the more complex ones.

I was wanting to make an NPC spawn when another NPC comes in proximity of it.
Basicly like this:

NPC - "A" - stationary.
NPC - "B" - moves toward NPC "A"
When NPC "B" comes within "X" distance of NPC "A" it will spawn NPC "C" at desired location.

I see how it is done with PCs... that looks easy. But not sure what to use or how to write with NPCs.