I would start regularly attending Alanon if you aren't already. The road to sobriety is their journey and theirs alone, there is nothing you can do to make sure they stay on the right path.
Rehab is usually the first stop, from there they should be going to an IOP for about 6 months, then a transition into daily AA. If this is just a rehab stint then dump back home without a solid plan in place, this can be a bad situation to return to old ways.