A 2000 Hyundai Accent is not passing DEQ due to Main Catalyst (efficiency below threshold (bank1))?

Explanation given was smoke, automatic transmission also wonky;shudders sometimes in low gear, delays shifting to upper gears (winding out). Synthetic oil for about 5000 est. Miles. little old lady duty life to and from church 1 mile away (seriously...she's 90). Help answerer, 10 point for most helpful, i vote personally too.