Backing out of a real estate contract

For reference we live in Florida, and I know laws vary by state.

My friend and her husband are selling their home. They had three offers on the table and one of the buyers offered over the asking price, so they accepted. The buyer signed a contract saying she had a certain number of days to get an inspection, and within that time frame she could back out of the contract and get her $20,000 back that she put down. After that certain amount of days, she forfeited her down payment. The buyer did not get her inspection within that time frame, and one day later decided that she didn’t want to buy the home anymore and that she also wanted her 20,000 back. She has been putting my friends through the ringer trying to get out of this sale, even though she signed a contract. Keep in mind, my friend and her husband bought another home contingent on the sale of their home, and they love it. Everything is already packed up and they are ready to close on both homes the week of the 19th. Every day this buyer is calling her agent, and calling my friend on her personal cell phone saying that she wants out of this contract and she wants her $20,000 back. Now she is always saying she will not come to closing because she doesn’t want the home unless they go down 100,000 in price. She’s out of her mind. What would you do? They also just had a baby 4 days ago, and this is putting a lot of stress on them.