Can the owner save herself from selling the house?

No, even if she wanted to pay a penalty she must sell the property once it is all agreed. Specific Performance means no other property is that property so she can't tell them just buy the one next door.
If they want out of the deal she can let them out or she might be able to pay them to not buy it. Think about the buyers, they already picked a house, quit looking, spent a lot of money on loan fees, gave notice where they live and started packing. She would need to give them enough to cancel the plans they made and work months on redoing with another property.

If she wants to keep the house, she will have to talk to the buyers to find out if they will allow her to back out of the deal. It will cost her a lot of money, though.

If the buyers do not agree and she tries to back out anyway, they can sue her to force her to comply with the contract that she signed.

I am not sure where everything stands. If she hired a realtor to sell the house, then the realtor is entitled to sell it for a commission. Also, in her divorce, the judge might have ordered the house sold. Not everybody is bright enough to think things through and accept that they have to sell it. I cannot make any judgments on this woman and her predicament but, good luck with it.

She needs to talk to her lawyer on this.

NO, not if she signed a contract

nope

Not without getting sued. She would be in breach of a legally binding contract. You cannot just back out of a sale with no penalty.