@mmodirni
Do you or your brother have a healthcare and financial power of attorney for your mother? Hopefully you had all of her legal documents updated after your father died.

If you have powers of attorney, you could work with her doctors to come up with a plan to ensure she gets the care she needs. You could ask them to speak to your mother while you are present (brother in person and you by phone) about her condition and safety risks. If they can help get your mother into supervised care, that would help relieve the burden on you. Her living alone may cause her to not take her medication regularly or at the right dosage/frequency. Not taking her medication can make her symptoms worse.

I experienced this with my mother in law. She was 85 and had Alzheimer’s and insisted she did t have it, didn’t need help, wouldn’t take her medication (hid it in the couch cracks), started to wander/get lost and thought she was 24! I was afraid she would forget and leave the stove on and burn herself or burn down her apartment complex.