An overdose of metformin alone would be the most painful thing I, as a metformin user, could imagine, and I've been plenty suicidal.
I don't know, OP, if you've been digging in someone's medicine cabinet for that odd mix, but it sounds like you haven't taken metformin before, to be including it. It's just a cheap generic drug for diabetes, that prevents your liver from releasing glucose after you eat. It also somehow blocks some glucose from being absrobed by your guts.
This means the glucose that you eat stays around in your guts. Where all the bacteria eat it. And grow, and poop. And go to war with each other over who will control the new glucose supply. The results is a couple years of cramps and bloating and truly epic gas. Whatever you thought was epic, is not.
Cancer patients enrolled in clinical studies to test it as an adjunct to chemotherapy dropped out to avoid more metformin. They chose chemo and an earlier death over metformin.
Your house and most of your neighborhood would probably be wiped out in the explosion from a metformin overdose; but keep in mind how long and painful it would be to develop the necessary volume. I imagine somewhere equivalent to being at the bottom of the Mariana Trench in terms of pressure, before your skin is finally stretched too thin for containment.
It's the equivalent of death from lactose intolerance, but from sugar intolerance. I don't recommend it.
OH yeah, the other drugs: if you try to OD on norco you'll just hurt pretty bad, wake up in the hospital with serious liver damage from the acetaminophen in it, and maybe have a shorter, but long life of complications from that. Bad idea.
Soma's just a muscle relaxer, right? Why would you want to pee and shit yourself if you're already depressed?