I'd start by making sure you have found whatever ingredients in the energy drink other than the caffeine draw you to it, and either make sure you are getting them in your diet or supplement. I had a looksie at the ingredient list for the Monster Rehab and things you might want to make sure are dialed in right off the bat in your diet are the b-vitamins and amino acids by making sure you eat some liver and maybe heart a couple times per week.
Secondly, cut the coffee down to 1 cup within a week or two. I've found that the first cup brings the wakefulness, and the second cup and beyond to either do nothing or cause a sort of cranky backlash fatigue to set in.
If you feel like you need to be more awake try Celtic Sea Salt salted bone broth first thing in the morning (if your adrenals are shot, you'll really feel the jolt from the salt), followed by a dose of eleuthero ginseng extract (which brings a deeper energy than the caffeine, I can even feel it if I've already maxed out on caffeine, and it also happens to be one of the ingredients in Monster Rehab). You can add a second dose in the afternoon if you get hit with a case of the afternoon sleepies. The eleuthero can take a week or two to feel the full effect, but it is worth keeping up on it to get to that state. And, the usual disclaimer, if you are taking any meds talk to your doc or a pharmacist before adding new herbs to your routine.
For the vitamin C there is always citrus or you can eat or juice some raw greens and herbs.
Best of luck!