Help me find maternal ancestor that died in an asylum in Illinois?

Her name was Goldie Marie Sanders. Her husband was James Irving Gilbert. The dates on Find A Grave seem to be accurate.

https://www.findagrave.com/memorial/90127429/goldie-r-gilbert

If there is a better place to ask this, please let me know. This is an ancestor that my mother recently told me died in an asylum in Illinois. I asked why she was in the asylum and she said epilepsy, but I'm skeptical of that.

She died awfully young. Her husband married her nurse, nearly 30 years her junior, after she died. I have no idea how to look up any more info regarding her death and time in an asylum. Nothing of much use is coming up on Ancestry. I can't find a death certificate or records of her being anywhere.

I have no idea what asylums were in the area at the time or if it's possible to get records. I see her headstone says "grandmother" which leaves me wondering if her husband didn't even bother to put up a headstone for her and it was just her grandchildren who put it up. The middle initial on the headstone is not correct. Her middle name was definitely Marie not R.

She is on the 1950 census in Pawnee, Illinois. But she's dead two years later and was in an asylum between then? Any idea how to document this and find out if it's true? I have no reason to not believe the story. But my mother was a child when this happened. Her info would be second hand. She remembers the step mother from the asylum.

But what makes me question if it was really epilepsy or not is that there is a history of mental illness. One of her daughters had some degree of mental illness where she spent some time in a hospital for it. And one of her younger sisters killed herself at just 16.