You should try writing it on one of the following topics:
Foils (Krogstad and Helmer, Mrs. Linde and Nore)
Comparing and contrasting the relationship that Nora has with Dr. Rank and Torvald
Use of light throughout the play
The many references to the play’s title (dolls), and the references to dressing things up like dolls, beauty’s importance, and nora’s role
use quotes and stage direction to prove that the Helmer’s house is a doll’s house that Torvald plays with and nora is but a doll inside of it
use of repetition throughout the story (repeated lines such as Krogstad’s questions about courage)
The symbol of the Christmas tree as a sign of family unity
Theme of heredity
Beauty vs. Ugliness and where the characters stand (is nora beautiful or ugly? Mrs. Linde? krogstad?)
The importance of the letter and the mailbox
Prove the fact that A Doll house is not a feminist play, but rather a human rights play (check out some quotes from ibsen for help on this one)
take your pick, and good luck!