The brief
The B200 had a humming or growling noise that increased with road speed, a vibration through the steering wheel, signs of uneven tyre wear, and the wheel feeling a touch loose or wobbly. Those are the signs of a worn wheel bearing. The bearing lets the wheel spin freely while carrying the weight of the car at that corner, and as it wears the rolling surfaces roughen, which is the hum turning to a growl, rising with speed because the bearing is turning faster and working harder. Play creeps in, which is the vibration and the loose feel, and that play also wears the tyre unevenly. A bearing making that much noise and showing play has run its course, and left long enough it can bind, so it needs changing.
The diagnosis
On the lift the wheel on the noisy side spun with a clear gritty resistance and rocked when pulled top and bottom, the play you don't want, while the others felt smooth. So it was the bearing, confirmed. That's a replacement on the affected corner. A worn wheel bearing only gets worse, and you don't want play at the hub at speed, so it was getting changed.
The work
The brake calliper and disc came off, the old hub bearing assembly was unbolted and lifted away, and a new genuine Mercedes-spec hub bearing unit bolted on in its place, the axle bolt torqued to spec and the brakes reassembled. The hub was turned by hand to confirm it ran smooth and silent before the wheel went back on. A road test confirmed the noise was gone, smooth at every speed, the vibration gone, and no play at the hub.
The outcome
Noise gone, smooth at every speed, no steering vibration, and no play at the hub. The B200 went home quiet again. A wheel bearing gives you a good warning before it lets go, so acting on the noise meant a straightforward swap rather than a wheel problem at speed.