Help needed about bypass capacitor

The solenoid's response time is perhaps 5 to 20ms. No need to worry till the cable is 50 miles long! There simply isn't any chance of picking up enough low frequency noise than can affect a solenoid or its driver transistor in that length of cable. (Actually a 50 mile cable would have too much resistance, as it happens)

And a long cable itself acts as capacitor. The TIP transistors base-emitter junction and base-collector junctions will also have capacitance come to that.

For logic signals (where the rise time is perhaps 3ns) then there will be all sorts of issues with crosstalk, noise injection, signal reflection, but an output to a slow mechanical device is automatically low-pass filtered by 6 orders of magnitude or more, so should be fine.