I don't know. The close answer is
mols sucrose = grams/molar mass
Then M = mols/L SOLUTION. Dissolving the solid in 100 mL ethanol makes the SOLUTION greater than 0.1 L. I'm sure the author of the problem meant for you to ignore the difference and use 0.1 L; however you need to be aware that M is mols/L solution and NOT mols/L.I am especially picky about this point because many students don't realize there is a difference between adding a solute to 1000 mL solvent vs adding solute to enough solvent to make 1000 mL solution.