this could maybe be done. i dont have any quests on the toon i have logged in right now though.
using the quest window TLOs you can pull the strings of text, but unless it specifically just says the name of the npc and nothing else, there would be too much variation for it to work well. and i dont think the quest windows do that, think it always says some string of stuff like "find AxeFace behind the shrubs". im not aware of any portion of string management that would make sense, but you might be able to pull individual words out of strings using space as a separator? i dont know if theres a better way.
but, if you overcome that, you could then
/nav spawn StringWordOne
/nav spawn StringWordTwo etcetc
then run a check to see if your moving before checking the next word on and on.
but this will also introduce you to running into other npcs or something too
"behind quarms dog house youll find zeb, go talk to that crazy guy"
and then youd nav spawn into quarm instead of zeb.
all in all, i dont think id try to make this although its interesting. lots of room to mess up and not do things right.