There are 3 main ways the group can escape the horror and survive:
1. Find a way to repair the generator and call for help. Normally, help should arrive 48 hours after the call, given the cabin's distance to any population center and the unlikelyness of the situation. If the characters manage to convince the national guard that the creatures are real (Difficult), then a helicopter should arrive the following morning. This win condition still requires the survivors to get on these vehicles, which should be attacked by monsters on arrival.
2. Kill the Woodsman, survive 6 days until the Aberration's breeding season ends, and destroy the cabin so the sin sprites stop surfacing. Requires the party to discover the origin of the sin sprites, which can only be done if they find Steph's dad's personal documents regarding the true nature of the cabin in the owner's bedroom.
3. Flee the location on foot. The hike through the dangerous woods would take days and be a serious test of survival. Abberations and Sin Sprites haunt the forest.