What changes are evident in Nora by the time she walks out the door in Act III?

The biggest change we see in Nora at the end of the novel is her own realization that she needs to start making herself happy before she can actually make anyone else happy. When we first meet her, it's all about keeping the house clean, taking care of the children, and getting her husband out of the financial problems he created for himself. By Act III, we see her refusal to play along and play act. We also see a woman who needs to find out who she is and stop being what everyone else wants.

"I have been performing tricks for you, Torvald. That’s how I’ve survived. You wanted it like that. You and Papa have done me a great wrong. It’s because of you I’ve made nothing of my life."