The lady that was shouting was a lady the Elie knew form his town. Her husband and older son were deported witha different group of people by acident and since then she has been going crazy. in the cattle car she startes shouting about seeing flames even though there is nothing.
The flames symbolize what is happeningto millions of jews and their towns. They jewish people are being discriminated against and killed. after they have been killed their bodies are cremated.
the woman representes how almost all of the people feel about what is happening. they know that if they have to go through any more they might go crazy soon.