Earlier Mrs Wilks had made a 111 call. She was coughing and was told by the 111 operator to leave the house.
The house was well alight when the Fire Service arrived with "heavy smoke and little visibility".
Investigators found the fire started in Mrs Wilks' bedroom; there was no plastic outer cover on the multibox and the age of the electric blanket couldn't be determined.
The coroner noted that if able, it would have been preferable for Mrs Wilks to call 111 after leaving the house, and a working smoke alarm could have given her earlier warning of the fire.
"I note GP Dr Scrimshaw's comment that Mrs Wilks had significant disability from rheumatoid arthritis and she was unsteady on her feet and used sticks to assist her in walking.
"That immobility would also have been an impediment to Mrs Wilks quickly evacuating the premises in the frightening situation she encountered when the fire started in her bedroom."
Mrs Wilks was a described a "delightful, kind woman of sober habits by her GP.
Rheumatoid arthritis made her unsteady on her feet and she used sticks to walk.
The coroner ruled the death accidental.