Hello Experts! I am swing back to this project.
I did not review the earlier part of this thread but am just responding to the new rendering.
Problem with the design below is the vent under the tub goes horizontal. Is this ok?
No.
If the run length to the wye where the tub drain joins the lav is short enough, then the lav can wet vent the tub as well as the WC. If you need a longer allowable length, you can use a 2" tub trap and trap arm instead of 1-1/2". Massachusetts has its own plumbing code, so you'll have to check it to find the applicable limits. [But the fall is always limited to one pipe diameter, so the maximum allowable run is never more than 6' for 1-1/2" and 8' for 2", based on the exact minimum 1/4" per foot fall. Some plumbing codes have shorter allowable lengths, perhaps as a recognition that the fall will rarely be the exact minimum.]
If you need to reduce the run length you could have the trap arm for the lav go to the right (as you face the lav) to a san-tee to the right, then the tub/lav wye would be closer to the tub.
Or if you prefer a dry vent takeoff, you could put one "around the corner", just use a wye (or combo) rolled 45 degrees for the vent takeoff, just like the one where the lav joins the tub drain.
Cheers, Wayne