If thats her concern, its better to protest now when they havent started deploying troops and we have a chance to gain support and stop them rather than later when its not an option.
Inaction out of fear is cowardice, but fearlessness and dismissal of the possibilities is equally stupid. Bravery is to understand the risks but overcome the fear. Recall the poem by Niemöller, "First they came for..." and take the necessary precautions.
Dont bring your phones (or keep them turned off the way there and back), disable biometrics on them, cover your face and other identifying features, and stick with a group. Keep everyone in your group orderly; no rioting or damage to property. Decide on a meetup point in advance for if you get separated.