if they are rx'd, take them how your dr tells you to take them. dilaudid has a poor oral bioavailability, meaning once it passes through your stomach and liver and everything, not much of the actual drug end up getting to your opiate receptors. the risk of becoming dependent on opiates has many factors, so its hard to give an exact answer, but its safe to say that if you are taking the lortab and dilaudid together every day, you will be physically addicted at some point. could be 2 weeks, could be 2 months. some peoples brains are "hardwired" more to accept opiates, just like some people are predisposed to addiction.
as for the pharmacology of the dilaudid, its short acting with a low oral bioavailability, it should be out of your system within a matter of days, its not going to build up a high level in your body. As for the valium, is that rx too or for recreation? mixing all 3 of those drugs are cns depressants and could lead to respiratory depression which could lead to you not breathing if taken in high enough doses.
waiting 7 to ten days with the valium is a good way to not get addicted, but if you take a high dose of it, the half life is massive compared to other benzos so it will take a long ass time to be fully excreted from your body. hope that helped.