@manishrpvv,you must have received an OTG cable(mini-USB to USB) cable along with the Tablet,I presume.
You just need to buy an USB-to-LAN module,which will cost between and max. Rs.150/- ~ Rs.200/-.
Just connect the USB connector of OTG cable(provided by the Tablet) to one end of the USB-to-LAN module and connect the RJ-45 ethernet jack of the ethernet cable,to the RJ-45 interface of USB-to-LAN module.
Go to the sttings menu of your Tab,while the ethernet (network) is on.Provide your ISP settings as given by MTNL(login ID;Passwd;etc.)
Hopefully you could enjoy the full network access onto your Tablet,albeit at limited mobility of your position...