What is the connotation and the denotation "The Cask of Amontillado" and what would be your opinion about the conclusion of the story?

To answer this question, one must understand what denotation and connotation are.  Denotation is the literal or "dictionary" meaning of a word.  Connotation is the emotional or subjective meaning of a word.  For example, one can look up the definition of the word spider and find the literal definition (eight legs, arachnid, etc.).  However, if one would ask me to define the word spider, I might say that it is a scary, creepy, eight-legged creature LOL!  Connotations of words are different for different people.

The literal meaning of the story is that Montresor had a grievance against Fortunato.  He hatches a plan to exact revenge and lures Fortunato to the wine cellar, where he gets him drunk and bricks him up, leaving him to die there.

The connotative meaning is different for different people, obviously.  The connotative meaning for me is that Montresor exacted revenge on Fortunato that is not warranted, mainly because we do not know what, if anything, Fortunato did to upset Montresor.  Also, revenge is never healthy and only causes grief for anyone involved in it.  It does not solve problems between people.  It only exacerbates them.