This particular kill count is interesting and a little difficult because there are several instances where harm occurs to people, but the ultimate state of their being is never really revealed. Considering we see Black Widow who has no powers or enhancements survive several instances where she should have died with no injuries in the movie, we will err on the side of survival on the uncertain cases.
20:37 Yelena kills a widow with a knife
38:22 Dreykov makes a widow commit suicide by wrist weapon
59:28 Yelena kills a machine gunner with a rocket
1:44:41 Melina takes out a catwalk with 9 guards on and around it causing it to fall into an exploding engine and then to the ground miles below.
1:50:57 Three guards dive after Red Guardian and Melina shooting at them, but I see no parachutes, so dead.
1:54:03 Copter with Dreykov and 10 guys blows up. It is also about at this point that I will count anyone I think is caught in the Red Room as it falls. Yelena knocks out 3 guys in the OR and a guard in a hall. I have a feeling they did not get rescued before the Red Room fell.
Total: 30