Doris Coulson remained spirited even as her illness progressed — watching cooking shows on TV, working crossword puzzles and wheeling herself down the hallways of her nursing home to show off her granddaughter when she came to visit. Coulson had been admitted to Hillview Post Acute and Rehabilitation Center in Little Rock, Arkansas, in January 2016, after Parkinson’s disease left her at risk of choking when she swallowed. That April, the facility’s operations were taken over by Skyline Healthcare, a New Jersey-based company that was buying up nursing homes across the country. Medical records for the retired cardiac nurse, then...