Suggest Treatment For Mental Illness

I have an aunt who has delt with mental illness for along time and she survived through it....but that is no longer the case. She has worked at her job for many years....she has stopped going to work, locked herself in her home she has boarded up her window and painted her skylight black because she says someone is trying to get her. If she doesn t show up to work or sign paperwork for retirement she looses everything. What can we do to get her evaluated,