Divided xp was 159 between 3, so 477 total xp
100 xp for the scout, 75 xp for the 3 guards, 200 xp for the 4 zombies, and assuming the wizard was 50 xp, total combat xp is 425. 50 extra xp for the zombies with heavy armor and 30ft radius bullshit explosions? Also no xp for obtaining Wester's bracelet despite being a very clear character objective (pgs 81 and 260 of the DMG), and an uphill battle for the past few weeks. Not asking for the players to find a treasure hoard in the cart, but throw them some sort of bone.
Every single guard also has a crossbow with an extra +1 to hit (they have a +4 instead of a +3), while still retaining their high ac and low cr. The logistics of equipping every small-town guard with heavy armor and crossbows doesn't make sense with how poor everybody seems to be. Bandits have a much more balanced stat block if you want every guard to have a crossbow, but constantly throwing large amounts of low cr creatures at the players is deadly at any level.
5e makes a lot of suggestions that should be completely ignored, such as the encounter building rules, adventuring days, and treasure hoards that only give the players an ocean of money by level 10, with nothing to spend it on.