Lamar Odom -- RETURNS HOME TO KHLOE KARDASHIAN ... 'Listening to Reason'

Lamar Odom has finally returned home ... with Khloe Kardashian ... but he remains undecided about seeking treatment for drug addiction, TMZ has learned.

Odom returned to his L.A. pad Monday after going off the grid for several days. Sources tell us both Lamar and Khloe are inside the home and addressing some serious issues, including Lamar's out-of-control crack problem.

We're told there's still no talk of divorce -- and Khloe is determined to help Lamar get his life back on track.

One source tells us Lamar is "open to reason and listening to the people who love him the most" ... a drastic change from a week ago, when L.O. rejected an attempted intervention.

We're told no decision has been made on possible treatment, but Lamar is "receptive."

Lamar seemed to be in good spirits Monday night -- when he was spotted out on a gas run near the home and stopped to pose for a photo with a young fan.

We know ... several of Lamar's NBA friends have tried to reach out to him, but it seems for the most part, L.O. is keeping to himself.