In the movie, PL Travars had alcoholism, then got sick. I assume it was because he was trying to quit and was facing alcohol withdrawl. But then he coughs blood in one scene, then dies later. I wasn't aware death is a risk of alcohol withdrawl. How did he die?

Technically he died of influenza. But alcoholism weakens your immune system.

Coughing up blood can happen with pneumonia, which is a complication of influenza. You're possibly accustomed to thinking of influenza as simply "the flu", meaning a couple days off from work with a fever and a cough. But it has the potential to kill you, which is why the elderly and people with compromised immune systems are encouraged to get an annual flu shot.

http://www.merckmanuals.com/home/infections/viral_infections/influenza.html

I don't know where to ask this, so I asked it here since it is biographical.

Just want to point out, in hopefully a nice way, that it took me about 5 seconds to find PL Travers' Wiki page and see "her father died from influenza".

http://en.wikipedia.org/wiki/P._L._Travers#Early_life

When you don't know where to look, you can generally type it into Google, and something useful will come up. No snark intended, just trying to be helpful.