Definition of "the most optimal" is not clear. For me it means a balance between usability, sound quality and cost just in a way that happens to subjectively feel good for me. To be usable = It must work and it can be put together and adjusted by me without special tools, special software and special knowledge that must be hired.
I would use a few input analog mixer for signal routing. It gets as inputs
- the mic (a separate one, it's too tricky to try to use the one in a low cost headsets)
- my bass amp line output or the bass directly
- PC audio output.
The main mix result can be fed as well to possible speakers and mixer's headphone output.
PC's audio input doesn't get the main mix result, it gets only mixer's AUX output. Mic and Bass channels in the mixer must have AUX pots for making the needed submix.
If you happen to know nothing of mixers and its connections you must get local help to select the right model which fits to your already existing gear, the needed cables and adapters and to get the system started.
The said system can be used also as a "record one track at a time" recording studio if you get an audio workstation program. But the sound quality (noise, distortion) is limited by the integrated soundcard of the PC. High quality sound needs a high quality audio interface and also high quality mics, sound sources and speakers.
In theory you could work also with an audio interface as suggested already by others, but no quarantee for its routing possibilities and working with a video conferencing system. The analog mixer approach is free of software compatibility problems.
BTW many analog mixers can be used also as USB audio interfaces. The quality and capablities vary widely between different models. But that's another story.
