Is the "lot" just land or is it a dwelling unit?

If it's just land (I tend to think not based on the info you presented) and the client sells their dwelling unit within 2 years you can retroactively amend and exclude the gain on the sale of the previously attached land.  See 1.121-1(b)(3).

https://www.law.cornell.edu/cfr/text/26/1.121-1

Go through the examples and see if anything fits your situation.

Rick