Does she receive SSI/SSDI? If not, she should be making an application for this so you are not as financially responsible for her and so she has access to things that are only available to folks receiving this type of money.
I would also contact your county's mental health department to see what is available in your county. Additionally, there should be an Aging/Elderly Department you could check with as well. Finally, I would see if you cannot contact the dr. at the last place she was hospitalized to see if they have any information on help that is available.
Good luck!