Bathroom Exhaust Fan with Light - Wiring
This is fairly simple
Your fan brings out the neutrals for the light/nightlight and fan separately for cases where they wind up on two different circuits or on opposite sides of a GFCI.  Since you only have a single circuit, though, you can simply wirenut both the fan and light neutrals to your white incoming neutral inside the fan's built-in wiring compartment and land the bare wire from that cable on the fan ground terminal, then wire up the hots as you'd wish.
Personally, I'd forego the nightlight myself, which means you cap off the blue wire, then connect black to one incoming switched hot and brown to the other incoming switched hot.  (If you wanted to use the nightlight, you'd put the fan and main light on the same switched hot, then use the other wire in the cable to bring always-hot to the nightlight, taking one of the switches out of service in the process.)  Obviously, you'll need the appropriate clamp or fitting for where your wiring enters the fan's terminal compartment, as well.