Regarding I94 issue if H1b visa valid for 2 months having petition approved for 3 years

Hello Friend,

I am planning to travel to india in July, I have stamped visa with company A till Sept 2017 and having petition approved by company B till Nov 2019.

if i travelled to india what will be me I94 date, it will be my Visa date sept 2017 OR my approved petition date Nov 2019.

if i got the Sept 2017 I94 date ,then i have only 2 months for extension,so do i need to file new extension OR i can extend it by nearby PBC office?

Thank you,

Appreciate your help.