Folks at XDA have yet to release a straight forward root method for Samsung Galaxy Grand 2, but you can get root on your phone by flashing a pre rooted firmware. This ROM is fully stock and is pre rooted, which means you get the usual utilities like Super SU and busy box pre installed.
Instructions For Getting Root on Samsung Galaxy Grand 2
1) Download the ROM zip
2) Extract it in your PC
3) Download ODIN from here and extract it to your PC.
4) Put your phone in odin mode ( holding volume down , home button and power button simultaneously ) and connect it to your pc through data cable
5) Place the rom extracted file in AP column of PC ODIN
6) Click START button in PC ODIN and wait till flashing completes ODIN shows RESET " PASS" and phone reboot automatically with pre rooted firmware
7) You finally have root on your Samsung Galaxy Grand 2.
There is only known issue that is related to Wi-Fi. To counter that, just input all the Wi-Fi settings manually.