Depends if you're staying within your macros/cals. There are better options like cottage cheese or straight up casein protein. The only real issue I see is eating carbs late at night is usually not good for weight loss or keeping fat off.
I'm in your same boat though. I'm a medical MJ patient and only use before I go to bed to actually get to sleep, but I usually wake up 4-5 times a night and cereal is so damn easy to make. When I'm bulking, I'm not too worried about it, but when I'm cutting I'll get my diet in check more.....meaning no late night cereal splurges.
Pretty broad answer I know, but hope it helps.
If you think you can, you're right. If you think you can't, get yo mind right!
Stay within your targeted calories/macros (like Kyle stated) on a daily basis and you can have that cereal before bed.
"I don't train really to win contests. I don't train to win friends. I don't train to look pretty. I don't train to look at some chick's ass. I train and train very hard cause it's uncomfortable. It's painful. It's demanding. I like that. Time to bleed." - MG
I don't think there is enough fiber in 2 servings of cereal. As far as how much fiber you need depends on your diet. If you are a meat and potato person, then you'll need more fiber than someone that eats a lots of veg's, fruits...