Why did she move back home?
She had just been at the beach with her family the day before looking happy and healthy. Then she leaves the next morning intending to only be gone an hour. She wasn't dressed for a jog, so there are only a few things you dip out for an hour for that I can think of:
1. Cigarettes
2. Groceries
3. Coffee
4. A fix
5. Feed someone's pet
6. Emergency
Another thing, on the 16th she says she is going back to Jacksonville to live, indicating she was somewhere other than Jacksonville (NC?). She posts a video two days later of her back yard. Where is that? It has a giant pond ringed with trees only steps from her back steps.
Finally, on Aug 26th she posts a picture of a cake "this guy" made her. She has what seems to be a boyfriend in Lancaster SC, BE, who she has a selfie with on July 9th.
On June 24th she was in Fort Lawn, SC.
So when did she arrive in NC? A clearer picture of her movements leading up to this can help us get an idea of where she has friends, why she was moving around so much, and where she could be now.
Now for the drug connection, I believe Abby did not do drugs as her friend/family is telling us and we should respect that. (At least definitely not heroin). Her friend Christina overdosed this past summer which is likely where the interest in drug prevention is coming from. If you read Christina's timeline, look for a post by JH around the time she was found. It is unclear if Abby was in Florida when it happened but she was not already in NC since her family is saying they miss her in comments under Abby's memorial post about Christina.
Abby was last seen getting into a brown Buick in the area of East 9th Street in Lumberton, according to Captain Terry Parker with Lumberton police. Who might own the brown buick? I agree with Cherry, her cell phone records are important here. What do the pings say? When did activity stop?