Ice cream will have lower freezing point than ice. this can be understood with the concept of freezing point depression, which is a colligative property. Colligative properties are those which depends upon number of solvent/ solute particles. Ex: elevation in boiling point , osmotic pressure. If we add a nonvolatile solute in a solvent, its freezing point decreases. In case of ice cream we add sugar which lowers its freezing point, aa sugar is a non volatile solute.