I KNEW IT! THE REASON MARIO & HIS MOM GOT INTO A FIGHT IS BECAUSE SHE'S BACK ON THAT STUFF!

Kikster.com managed to track down a friend of Mario's who broke down what ALLEGEDLY happened between Mario and his moms - that got him arrested.
This is what the friend said:

While Mario was of town recording in New York, his mother had relapsed back into drugs and she was using his personal debit card to purchase illegal narcotics, aka heroin. When Mario returned home (on the 25th of September) and confronted his mother about her actions she became enraged and an argument escalated, his Mom called 911 claiming that Mario got physical with her.

And Mario's official representative chimed in to say the following:

Since Mario's release on bail, Mario has returned home and is working at getting his mother back into a treatment center for her recent relapse for drugs.

"This is an unfortunate incident between a loving son and a mother who continues to struggle with a devastating addiction. Anyone who has waged the battle to save loved ones from the forces of drugs knows the irrational behavior that almost always accompanies their actions. Despite the allegations, Mario remains committed to supporting his mother.