If you sold the home in 2018, you can report the sale and select that it was involuntarily condemned. It will not postpone the gain, but it will calculate a partial (or total) capital gains exclusion.
After you enter the 1099-S, go through the following interview. Eventually you will get to the screen to select that situation. (please see screenshot).
Postponing a gain would involve a 1031 exchange which is not available for a personal residence, only investment property.
