You each get a separate $250,000 exclusion on the home you owned previously. She would use her exclusion only on home B, and then you can use your exclusion only on home A. Then in the future, you would have to wait 2 years from the sale of home A to use what will then be a combined marital exclusion.
However, if the gain on home A will be more than $250,000, you have the option of combining your exclusions for home A and paying the gains tax on home B.
Also, because of the rental period, you will owe some depreciation recapture on home A that is not subject to the exclusion.
