None of these options are particularly terrific.
Options B and C have the same problem, in that they assume that Macleod Trail can be pedestrianized, but it can't be along the south-of-Beltline stretch. Nobody's going to be hanging out on the lawn between Macleod and the tracks, as illustrated in B, so that's going to be a dead zone.
Option A protects pedestrians best, but I worry that the under-bridge area will also become a dead zone, particularly in the winter. Yes, these are illustrations, but think about all of the other under-the-bridge areas in the city and how dead they are: East Village, below the Sunalta overpass, under Centre Street…
Option A is probably the best compromise, but it's also the most expensive of the three, I'm sure. I like that it creates a barrier between Macleod and the more pedestrian train area.