How often should this maintenance occur?
What is included in maintenance b? on 2009 Mercedes-Benz ML350
The list is shown in your own manual that came with the car. You did not give the zip code where you are at so could not look up estimate for your area. Here in Oregon is $250-$375. You can look it up yourself on the home page estimator link for your zip. Learn to use this site for easy things like that and do some research on your own at the home page. Depending on the shop you take it to, their labor rate and how much you do on the list and quality of parts/fluids will make a difference on the cost.