C.,
You write in your SWH, "she is isolated with just baby sitting her grandson...."
Seriously? Someone allows her to watch a child???? I don't know how old her grandson is, but she is in no condition to be babysitting a small child, if her condition is as bad as you report it to be.
Her medical and psycholgical conditions cannot be diagnosed without proper evaluation. Talk to her husband and come up with a plan. Call social services and the state mental health hotline. Give them the information and ask them what the next step would be. Laws differ by state in terms of involuntary commitment, so you have to see what the rules are in the state where she lives.
If she called the hospital and police, there must be some record of their response, at least the police response. Follow up, and get any available reports. You may need them, if at some point in the future you go for involuntary hospitalization.
In the meantime, do what you can about keeping that child safe. Social services may need to be involved on this front, if no one else in the family will step in and stop this, and that might be your avenue to get her to the help she needs.
Best to you and your family.
J. F.