You can give the money to "whoever" you like.
D. No improvement
Book says C but I am confused between B and C
The correct answer is B, "whomever":
You can give the money to whomever you like.
The objective case is required because who is the object of the verb like in the embedded clause whomever you like. That embedded clause in turn is the object of the preposition to.
It is a common error, in a sentence like this one, to believe that the preposition to governs the case of the pronoun. Instead, it is the structure of the embedded clause that determines the case of the pronoun. For instance, if the sentence instead were:
You can give the money to whoever comes first.
...the subjective case whoever would be correct, because here who is the subject of the verb come in the embedded clause that is the object of to.
Neal Whitman of Literal-minded has written a piece for Grammar Girl on this subject, and for those who prefer a spoken answer, a link to the podcast is here.
Mr Whitman's own blog features an entertaining piece on the subject as well, and those who are interested may read it to learn why it is entitled Whomever Is Never Actually Right.
(Note that in modern spoken English, the objective whoever is often used no matter what case is called for by an embedded clause, and the "requirements" of formal grammar should not trouble anyone who chooses to use it.)