Good afternoon to you, WarriorMoo. It is common for domesticated felines to bring in dead animals into their house as an offering so, that'll put a stop to anyone ranting of cats in general. Anyways, the best thing to do is to rehabilitate the young rabbit but at the same time, releasing it won't help seeing as how the mother won't recognize and try to consume it since they'll confuse your scent or even your mother's scent with the baby. The consumption of young is common amongst rodents and even if the mother doesn't eat it, it'll ignore it and the baby rabbit will end up dying.
I'm not concluding that you should keep it but it has less chances of surviving out in the wild at such a young age seeing as how it'll be invulnerable and such. You might want to foster it for a while until it gets older and release it, but that'll be a problem as well...
Sorry, this is all the information I can provide and I wish you the best of luck.
Have a nice day,
-Soar.