Burning Down the House

Sunday morning Pops and I took the kids to church and an hour later we were home. I opened the front door and their was a visible smoke layer through out the house and the smell of something burning.
"Mom, are you okay!"
"Yes, Judy, what's wrong?"
"Something is burning!"
I ran to the toaster oven and looked and it was very slightly warm and off. But clearly the culprit. Mom has a habit of broiling (vs toasting) her bread. She thinks it works better that way. There is a timer on the oven, it sometimes sticks. Or you can turn it on and it just stays on. Another piece of this is that as Mom has aged, she has lost her sense of smell.
" Oh, I don't think so. I cleaned the oven. But I don't think I burned anything."
Well I knew she had in that it was morning and all of the above.
"I am pretty sure I didn't cook anything but I'll try to find what it was."
Shortly she showed up with a charred bagel.
"This must be what burned."
She had NO recall of that event and it happened within the last 45 minutes.
"Mom, do you understand why I am worried?"
"Well of course! The house could have burned down."
She gets that.
But she doesn't get how unsafe she is.
Later that day we replaced the dead batteries in the smoke alarms.