What is most simple eukaryotic genome?
You asked about eukaryotes. The genome of the yeast Saccharomyces cerevisiae is 12.2 Mb.

The genome of the smallest free-living eukaryote, Ostreococcus tauri (a unicellular green alga) is 12.6 Mb

There are smaller eukaryotic genomes, but these are not free-living organisms they are intracellular parasites.