Another website had people arguing about what proof of alcohol would burn. Some claimed that 40 proof would sustain a fire, while others said that their 80 proof vodka wouldn't but 100 proof would. Considering that a blood alcohol level of 0.1% is legally drunk, and that converts to 0.2 proof, I doubt she caught on fire from drinking alcohol unless she had just drowned at the local distiller.
Whenever I make beef with red wine, I flambe the meat with cognac at one point.
The cognac is 80 proof. It is gently warmed first to release fumes that are lit with a match. The cognac itself doesn’t burn, and carefully I pour the flaming cognac over the beef in a wide pan. I cover it with a flame-proof lid to smother the flames.
So yes, 80 proof can catch fire, but it is the fumes that burn, not the liquid.