There's no inherent advantage to either band, except 2.4 GHz antenna can provide more gain per size. Both 900 MHz and 2.4 Ghz are unlicensed bands (at least, in North America). Once upon a time, the 900 MHz band was used for wireless headphones and speakers, cordless telephone and baby monitors, but these consumer products have mostly fallen out of use. These days, the 2.4 GHz is heavily used by WiFi. Which band has less interference depends on your local circumstances. 900 MHz equipment is more likely to be manually tuned.
If it was me, I'd get a WiFi version of the camera (not just 2.4 GHz, but specifically Wifi enabled). They're not that much more expensive.