Yes, coal has gone up considerably.
But, it's still not even close to matching the cost of oil, and Mom lives smack in the middle of anthracite central, aka Pennsylvania.
If I lived close to her, I'd be installing a dual fuel coal/oil boiler and would be building a coal shed out back for the coal. That way I could tend the boiler for her on a regular basis.
Unfortunately, I'm 180 miles away.