Does anyone know why she happened to be on that particular plane? Was it something routine for her?
The Hawaiian Department of Health (HDOH) was responsible for the leper colony at Kalaupapa, and Fuddy was the mayor of the county. She and her Deputy Director Keith Yamamoto were making an annual visit to the community. In her capacity as the official responsible for the community, she was also there to settle a dispute between the residents. In addition, her mother lived in the colony until her death ~1996/7 IIRC.
From what I saw in previous articles, Fuddy was visiting the sparsely populated island of Molokai to inspect the leprosy colony there, which. pursuant to Hawaii state law, was under her jurisdiction as the head honcho of the state's Department of Health. Her visit was reported as routine.
As to why she was on that particular plane, the intuitive guess is that she didn't really have any other choice but that one airline which flew passengers in that particular Cessna model aircraft between the two Hawaiian islands of Oahu (on which Honolulu, Fuddy's main base, is located) and Molokai. It's a very short flight, about 50 miles.