Masha Heddle is a pretty minor character in this book: she's just the owner of the Old Crossroads Inn, just a commoner. So why are we giving her her own entry when we don't pay too much attention to other commoners, like Moreo Tumitis (captain of the ship that takes Catelyn to King's Landing [19 Catelyn 4]) or Byan Votyris (captain of the caravan in Vaes Dothrak [55 Daenerys 6]) or those poor folks who testify to Eddard about Gregor Clegane's raids [44 Eddard 11]?
Well, Masha Heddle may be a minor character, but she's also a good example of how the common people get caught up in the fights of the lords: Masha doesn't want to be involved, but since Catelyn kidnapped Tyrion at her inn (29 Catelyn 5), Tyrion's father has her killed later. Now that's bad luck.
Also, even though Masha is just a blip on the radar, our author makes sure that we know she was a person with her own particular traits and skills; for instance, she chewed sour-leaf, which stained her teeth (which Tyrion still sees on her skeleton) and she brewed good beer. So her death doesn't change the course of the war, but it's a vivid little example of how the war has costs for people who won't gain from it one way or another.