PSA: keep essential oils away from your cats. Don’t pit them in them, and especially don’t use those vaporizers. Most of those oils are toxic to cats. If you want your house to smell nice, burn incense.
If you don’t have cats, go wild; there’s nothing wrong with the oils themselves, and they smell nice. But many are toxic to cats, and it can be hard to get a complete list of which.
Neither are going to protect or cure you of anything (except, perhaps, a cat infestation), but scent can be nice.