Sethe is in grave danger because of Beloved's death grasp upon Sethe's fragile mental and physical condition. "The thirty-eight dollars of life savings went to feed [Sethe & Beloved] with fancy food and decorate themselves with ribbon, . . . shiny buttons and bits of black lace" (240). Physically, Sethe is dying from hunger while she gives Beloved every ounce of the meager food she has left after their thoughtless splurge on frivolity. Sethe no longer has any knowledge of or desire for the future for her little family. Beloved has, literally, taken Sethe out of the real world and given Sethe only one goal: to plead her case to Beloved (indirectly) as to why Sethe ended her baby's life. There is no winning this battle, which is breaking Sethe mentally; therefore, Sethe wastes away to practically nothing.
The reason behind Sethe's salvation remains open to interpretation. A case can be made that the townspeople save Sethe from Beloved through exorcism. Likewise, one could argue that the simple disappearance of Beloved in itself saves Sethe. Yet another idea could be that Paul D saves Sethe through his strength by convincing Sethe, "You your best thing, Sethe. You are" (273).
Ultimately, however, it is Denver who saves Sethe. Denver, the girl who was always afraid to leave the house, now becomes Sethe's salvation by doing just that. "Little by little it dawned on Denver that if Sethe didn't wake up one morning and pick up a knife, Beloved might" (242). Denver has a revelation and realizes "so it was [Beloved] who had to step off the edge of the world and die because if she didn't, they all would" (239). Physically, Denver's emergence from the home sustains the family. Mentally, Denver's emergence from the home renews the family's strength. Indirectly, Denver's emergence sparks the "exorcism" that happens near the end of the book. Denver, then, is the savior in Toni Morrison's Beloved.