She returned from leave to find her job had been made obsolete–what are our obligations?

Q: “We have an office manager who was offered a position in HR dependent upon continued education. She elected to not stay in the role within HR. She had to go out on leave (non-FMLA), and during her leave of absence we restructured our regions and no longer have an office manager role—we are filling with a higher level admin support position. We have offered her other positions that she has refused. What are we obligated to do for this employee? If she refuses other positions, should we have a reasonable belief that she is not returning and has vacated her employment?” – Bobbi, Arkansas