What is IUPAC name of the following compound?

To name the cyclic alcohol according to IUPAC rules, the hydroxyl group is prioritized and assigned the lowest possible locant, designating the parent compound as cyclobutanol. The ring must be numbered in the direction that provides the lowest possible locants for the substituents, then ordered alphabetically.

Since the hydroxyl group is fixed at position 1, numbering clockwise places the ethyl group at position 2 and the methyl group at position 4, while counter-clockwise numbering gives the reverse. Both paths yield the locant set $(2, 4)$ for the substituents. Alphabetical precedence requires the lower locant to be assigned to the ethyl group, thus the ring is numbered clockwise.

Final name: $2$-$\mathrm{Ethyl}$-$4$-$\mathrm{methylcyclobutanol}$

Comparing with the options, the correct choice is $\boxed{\mathrm{C}}$.