Hi Arunkumar,
Create custom java action and pass user as input parameter to that java action and create the session,
ISession newSession = Core.initializeSession(Core.getUser(systemContext, user.getName()), "");
and then just make a cookie with that session.
Add page url to the web page and redirect it to that page from mobile.
https://docs.mendix.com/refguide/page-properties/#url
Hope it helps!!!