The most appropriate option to fill in the blank is no.

The word no means not any or not at all. In this case, the sentence is saying that my life has no meaning without you. This means that my life is meaningless without you.

The other options are not correct.

• Not means to a lesser extent than something else. It can be used in this sentence, but it would mean that my life has less meaning without you.
• Never means at no time in the past, present, or future. It cannot be used in this sentence because it does not describe the current state of my life.
• None means not one or not any. It can be used in this sentence, but it would mean that my life has absolutely no meaning without you.