In the two-part episodes There’s No Place Like Home, Lars Hanson suffers a stroke while many former residents of Walnut Grove were in Winoka. When they returned, they were shocked to discover that the town of Walnut Grove had gone into great disrepair due to his stroke oh, and she was unable to work or help the town but he recovered.
At the end of the episode, Laura Ingalls does a voice-over and states that Lars Hanson died 4 months after the Ingalls returned to Walnut Grove. While it’s not said specifically that his death was caused by the stroke he had months earlier, it is highly likely that his death was the result of the stroke he suffered, especially because strokes were still very misunderstood in that era.