Discuss the irony in of the following: W. Somerset Maugham’s The Appointment in Samarra, and Edgar Allan Poe’s The Tell-Tale Heart.

I will answer the question about Maugham's short story.
 The irony here is primarily situational.  The unexpected happens.  In trying to avoid
his fate, the servant actually fulfills it.  He sees Death at the market place, and
flees to Samarra.  Death explains to the servant's master that he was surprised to see
his servant at the market-place this morning when he had an appointment that night with
the servant in Samarra.  The irony is particularly effective because Death's response
surprises the reader with the unexpected, and we know that the servant's fate will be
the opposite of what he expects.  The irony works to show that
there is no escaping  fate.  When we think we are avoiding it, we actually are working
to make it happen. Oedipus Rex is an example of this type of
irony.

I'll let another editor respond to the "Tell-Tale
Heart."