I think that Pepper seems angry at your mom for leaving. My mom has a friend who is gone frequently and when she comes back, her cat runs and hides from her. I suggest giving the cat time to adjust back to having your mom back and maybe in your spare time, you can pet Pepper and maybe Pepper will feel better and start spending time with your mom again. It could be possible that Pepper is jealous of your mom for getting all the attention, after having you all that time. I hope this helps and other cat people will help you out too,