Oh, what the hell... Blanche has a nervous breakdown after being attacked and supposedly raped by Stanley. The rape is never definitely confirmed in the play, but implied strongly. Given Stanley's animalistic brutality, it is usually assumed that the rape actually happed, even though Stella refused to believe it. Blanche is committed to a mental institution, being now totally immersed in her fantasy world and severing all ties with reality. This is where Blanche delivers her famous line about depending on the kindness of strangers.

Hi Zaid, This sounds like an assignment or exam question, so my first advice to you is: read the play or at least see one of the films. Or the opera! Then watch the Simpsons episode for the laughs. If you *really* want to cheat (don't do this... believe me, you'll enjoy it much more if you see/read the whole drama), do a search on wikipedia.org ; there's also clips on youtube, including the final scene you're asking about.