Since she's so young it's unlikely she is associating any abuse she's had
Some dogs are more skiddish than others
and see friendly people coming at them to pet them as threats
Think of it thru their eyes ... these big hulking monsters with these big hands
Love her and treat her whenever she comes to you
as for strangers ....
have people socialize with her as much as possible
have them touch her and love her ... the more she associates good things with people the less she will be afraid of them
Alos skiddish dogs are usually afraid of new surroundings too so bring her out with you as much as possible to experience new things and smells