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Yes, publicly supported social workers are vastly overworked. However, if you can find one in your mother's county or city, that person will know what services are available, how the law works in that state for mental health issues, and so on. They may have some ideas you haven't thought of.
I think some of the other suggestions are good too... try the prescribing physician on your mother's medications, try a crisis hotline in your mother's city or county.
If it's any help, try to think of your mother as an adult who has reverted to toddlerhood. They do ridiculous, irrational things, and have to be protected. Unfortunately, your mother has the body of an adult, with adult privileges like driving.
Good luck.