Hello, Ganesh.
My opinion here is following. From The Nexus Guide we can see, that
Nexus has single Product Owner, who has the final say on the content
of the Product Backlog. So, the Product Owner in Nexus has to work with more than one Team.
Nexus also has the Scrum Master, which "may also be a Scrum Master
in one or more of the other Scrum Teams in that Nexus".
Also the Developers can work in more than one Team. So, if focus and commitment
values are still in place (!), I think, it is possible to serve as the Scrum Master for 2 teams.
I think, it also depends on whether these two teams work on the same product
and whether these teams have the same Product Owner.
But it is not the Scrum Guide restriction. It is about ability of the Scrum Master
to concentrate on his duties and to serve properly for each Team.