Well, depending on who she was, what information was on the laptop, and what it was used for, she could conceivably sue for damages related to lost time with the laptop and lost information.
If she were a business woman, and important business information was on the laptop, and that was the only copy of the information, and she had lost profits equal to $54 million dollars from going without the laptop for three months, she could conceivably sue for it.
If it was a personal laptop, and she had the last pictures of her father before he died on her laptop, and those were the only copies of those pictures, she could sue for it. I'd think $54 million is steep for sentimental items though.
I could see suing Best Buy for the inconvenience and run-around she received, just to show them not to mess with consumers so blithely. But still, $54 million is a steep pricetag for "teaching them a lesson." But then again, maybe you need a threat that large to get them to listen, in the only language they'd understand? But... still... will they change their habits if they lose this lawsuit and have to fork over that large sum of money, or will they continue to screw their customers, and try to find ways to hide it better?