I have made a custom follower and I would like the 'follow me' option to only appear once the quest associated with her is done, is there anyway to do this?

Here's a link to the original question over on the Nexus forums so you can read what I've already tried.

http://forums.nexusmods.com/index.php?/topic/2840879-adding-follow-me-option-when-quest-is-over/#entry25085369

iirc, it's the relationship or friendship faction. Make sure the PC isn't 'friends' with the npc until the quest is over.