Following the expression and use of distributive property, we get:
-2m^2 - 2mn + 8m - 10m + 10n + mn + 4n^2 - 5n.
Now we simply put like terms together and this would become:
-2m^2 + (8m - 10m) + (-2mn + mn) + (10n - 5n) + 4n^2,
giving the short form:
-2m^2 - 2n - mn + 5n + 4n^2
Thus the answer is C.