I doubt this story about the Instagram being hacked. If it was indeed hacked then Instagram would simply revert it to the day before the hack and reinstate it as it is a verified account. That is the point of verified accounts. Sounds to me that she/her agency/whoever needed to put some space in between the current stuff and everything she posted while under 18. This would make sense really as if she is moving to a more glamour and "adult" (not in nude sense but in content) mode in her career she can't be seen posting it up on the same account as under 18 stuff. Clearly she is a successful model but when you see the likes of Meika Woollard heading to the states to further her career in fashion and the body type of Emily then you realise that bikini, lingerie and cheaper fashion stuff is more Emily's hit level.
This is a reset made by decision and not by hack, that is my take on it.