There are really very few connections between William Shakespeare's "A Midsummer Night's Dream" and Ernest Hemingway's "Hills Like White Elephants".
Shakespeare's play was first performed on January 1, 1605. It is written mainly in verse, and set in a dream-like forest. Its characters are a mix of ancient Greeks and supernatural beings. It has a cast of two pairs of young lovers, the King and Queen of the fairies, Puck, and nobles and members of the Athenian court.
Hemingway's story was first published in August 1927. It is set in a modern European train station, a distinctly unmagical environment, and consists mainly of a dialogue between one woman and one man. It is written in plain prose. The relationship in this story is not embedded in a social structure, but is between autonymous human beings.
If you need to make a connection between the two for an assignment, you could explore the contrasts between the two works, or perhaps talk about the hills of the girl's imagination creating a dreamscape like Shakespeare's forest.