"Either" is used to mean one or the other and has a positive undertone. The sentence means that the person hasn't read the two books on the table. Hence option B is the correct answer.
"Neither" simply means none or not any. Using this in the sentence would lead to a situation of double negatives resulting in a positive sentence. Since using option A would change the meaning of the sentence, it is an incorrect answer.
We use 'each' to refer to individual things in a group or a list of two or more things. As we are referring to both the books on the table, option C is incorrect.
''All'' is generally used with affirmative sentences and using it in a negative sentence is considered poor grammatical structure. Hence option D is also incorrect.