Why was Mrs Walton not in the last episodes of the Walton's?

Mrs. Walton, played by Ellen Corby, was absent from the final episodes of "The Waltons" due to her real-life health issues. Corby suffered a stroke in 1976, which limited her ability to perform. Although she returned for some episodes in the later seasons, her character's reduced presence was a result of her declining health and the show's decision to respect her situation.