Can an inmate reject halfway house and do the remaining time inside

My wife's a American Sioux Tribe Indian, doing 19y 6m... She got a two point reduction and will be sent to a hallway house, after 16+ years in the BOP. Why can't she just finish her 19y 6m sentence and walk out the front door, FREE?? Why Can't she deny the hallway house, and supervised release. She's not going to get a job, pay a halfway house 25% of her pay, then 25% of her pay when she gets home, go to meetings, etc. If, anything, she'll run as soon as she gets on a bus to the halfway house, and will not be take alive! Tell me why she can't do the 19y6m sentence and hit the streets a Free American Sioux Tribe Indian? And how does she go about doing that, without having to be tracked down and murdered by the FEDS??? If you only knew what the Sioux Nation Indians feel about the FEDS, you'd understand. Why don't they? There's gotta' be a way to prevent this from happening, what is it? Thanks. I await your reply and remedy.