One of the worst sexual assaults I have heard about in my State was in an extremely expensive, nice area during the day.
I think the OP is out of line trying to tell her friend what she can and cannot do. She was walking through what sounds like a busy park. Why shouldn't she? What if her evening walks are paramount to her mental health? Loads of people go walking at night as part of their wind-down and debrief after work.
To the OP mind your own business. I seriously hate being told what to do, and I would de-friend immediately if someone went online and told the world how stupid I am for enjoying my walks through the park.