I can speak on the Trijicon brand ACOG - if you're looking to use a 'tactical' style optic, the ACOG variations available to the civilian market are a really good product (although a 6-700$$ price range). The product makes up for the price tag in the form of durability, good accuracy and excellent customer service from the manufacturers (which you likely wouldn't need). I have done a good deal of night shoots with the ACOG in the service & love those optics. I figure if they're good enough to hunt bad guys at night, one could whack animals.
In lower price ranges I owned an EOtech (non - NVG compatible: $375.00) and on lowest setting, with decent moonlight to backdrop the target, it worked great at night. It held a 200 yard zero and was also extremely durable - I sold that optic and the AR it was mounted on when I needed cash.
On a more humble budget now, I built another AR and have a standard ($100.00) X1 fixed power red dot which on low setting, worked great on low light / dark varmint shoots.
End the end it is up to you - I am a big fan of the ACOGs and red dot / holographic sights; if I were going to mount a reticle scope, I would go high - end (providing I intended to use at night) as the better quality scopes gather light much more effectively of course.
PS - Those illuminator / green light / spotter devices (if legal in your area) are sold on cheaper than dirt and supposedly work wonders. Illuminate the coyote's eyes & aim for the green reflection! I know a gentleman who swears by the effectiveness of those things.
Why? One inquires why? Because, AMERICA !!