At her age, if she is afraid of people that's not a good thing. It might be possible to tame her but some people say they couldn't tame theirs at that age.
I do know that it's going to take time; it could be weeks or longer. You never want to chase her, walk toward her, try to grab her or corner her. Just go about your business slowly while you are around her. She has to come to you!! You can talk to her or to yourself.
Take out some treats and sit down to eat while she's watching. Sometimes the lure of a treat will bring them close enough that you can feed her, even throw it over to her and she may eventually start to come closer and closer until you can hand feed her. Then, eventually you can slowly reach up to pet her. Never bring your hand down over her head, bring it up from underneath or the sides so she can see what you are doing.
If the other goat lets you pet it then make sure you give that goat lots of attention in sight of this goat. She'll see how much the other goat likes you and that may help her overcome her fear also.
If you get to the point where you can touch her most goats love having behind their ears scratched and between their shoulders scratched.
If you do take her back make sure you still have a goat friend for you other goat. They do not do well alone.
In the meantime just be sure that she can't get out as you are right, it would be really hard to catch her.
Good luck.