The main question I have is, why two routers?

For basic setups, Sonos speakers need to be on the same network/VLAN as the device that is controlling them . 

No. Sonos devices need to all be on the same subnet and that isn’t going to happen with two routers. Plus, as already said, “why two routers”?

Thanks for your reply.

When I searched sonos or sonos app, multiple homes displayed.

https://www.reddit.com/r/sonos/comments/1g474ye/new_sonos_app_update/

Because I understood multiple homes as different routers. 

What I want to know exactly is about multiple homes.

Could you explain multiple homes?

I assume that you are transporting the SONOS units from one location to the other. The easiest plan is to use the same WiFi username and password at each location.