Is my neighbor required to offer a fidyah or kaffarah for spending a night in the Haram, given that she did not trim her nails or hair before Hajj?

It appears that your neighbor missed two rituals of Hajj: shortening the hair (taqseer) and spending one night in Mina. As for missing the taqseer, there is nothing due upon her according to the more preponderant opinion, and she should now take a fingertip-length from her hair. The more cautious approach is to slaughter a sheep in Mecca. As for missing one night in Mina, many scholars hold that a "mudd" of food is obligatory for it, and the preponderant opinion is the obligation of a "mudd" of food. Trimming the nails is not among the rituals of Hajj.