who has to file?

My disabled adult daughter has been filing taxes for many years but she is now on disability and only earns minimum wage, working only 10 -25 hours a week.  I do all her financial handling for her due to her disability.  Her income last year was $4,873.  Does she even have to file a return at all?  If she doesn't, do I have to file anything letting IRS know why she's not filing?