This is a fairly easy mission.
*** Spoiler - click to reveal ***When you go to the roof of your fanily appartment, the game switches to you leaving as Miles, following Genkie to ypur mums rally. There's a fight with the Tinkerer's men, Venom punches and Gravity wells work well against them. There's several groups of them, clearly expecting Spidey to show up. They appear on the rooftops nearby as well as the street. So, you need to clear quite a few.
An explosion happens and after a fight on the bridge (same tactics as before) The bridge will collapse, resulting in a bunch of real time events, that you'll need to start again if you lose a civilian. This is a very Toby Maguire-esque scene. Once the cut scene is over, you get the trophy.