Hi Linda,
I'm no expert in trail safety, especially in the dark, but I would say any of the trails that parallel the roads closely would be your best bet. Dan Beebe starting from Hwy 162 in front of the spillway would be a good one. You can get there from town without too much of a drive, 10-15min. I think. If you run to up to the intersection of Canyon Drive and Royal Oaks and back, that will get you exactly 5 miles. You can cross the street and continue up the trail to get some extra miles in.
Bidwell Canyon trail starting from Saddle Dam Trailhead access would be good too, just a longer drive from town. Still not too bad though.
Josh