Elijah appeared (as a -1 instance). Since the frame was made for him, this instance was stable.
She had her husband back and lived with him for decades.
This particular instance existed all the way from the 30s and beyond her passing, so this "forever young Elijah" made of grief was the haunt of the mansion.
It ceased existing when the painting was stolen, prompting the -2 event that destroyed the mansion and resulted in the frame's apprehension.
No anomalous effect made her forget anything, just the sheer shock, followed by happiness.