Any way to eliminate smell from a vent stack
This will probably depend on your local code, but it can be done and is done. You have to cap the pipe appropriately, keep it a minimum distance away from windows and doors, and so on.

Here's an existing answer that may help:  https://diy.stackexchange.com/a/58659/24137

Another possible option is an AAV, or air-admittance valve. It only lets air into the pipe, not out. So it will allow air into the pipe to perform the same function as an outside vent pipe, while preventing gas pressure from the sewer from pushing smell/toxic fumes into the dwelling. The use of an AAV will very much depend on your local code and your inspector. The one time I did this, the inspector required me to run the AAV 4 feet higher than the line being vented.

AAV's can wear out, so you don't want one closed up inside a wall where you can't access (or even find) it. So where do you locate it? In some cases you can locate them under counter tops. That might work fine for a sink. But you're also talking about venting a bathtub or shower and a toilet. So you're talking about a pretty substantial vent pipe and a large AAV. Definitely talk to your local inspecter first if you consider going this route.