actually it's a matter of situation.. if you want to shoot low light conditions without tripod and it's a portrait shot than the 50mm is good.. Kit lens for landscape night shoots are a-ok! Just remember to put f8.0 and use a tripod.
Settings:
ISO 100
Shutter Speed: 15 Seconds
F Number: f11
Focal Length 18mm
Lens: 18-55mm Kit Lens
Body: Canon 1000D
Night shot using 18-55
unfortunately no exif data.. so can't tell you whats the settings but I know it's f11.0 not sure how long exposure. It was stitched together too.. so not really a good example but it shows you what you are capable of doing.
Night shot using 50 mm prime
settings
Make: Canon
Model: Canon EOS 1000D
Shutter Speed: 1/256 second
F Number: F/2.5
Focal Length: 50 mm
ISO Speed: 400