You can use Tapatalk BYO option which is costly or Forum Runner which is costly as well. Xenforo responsive design is quite good and will suffice well, but not in cases where users have low speed internet on their mobile devices which is extremely common in India.
Here apps like Tapatalk will come to your rescue. If you are starting out better get Tapatalk Free. I have used it for long. You can use their inbuilt ad-system as well to earn, but I am not sure of the earning potential in it.
The only forum script with a dedicated mobile app is Vbulletin if I am not wrong. But well VBulletin has long since last its charm, Xenforo has literally made them bite the dust, you can see for yourself since many large Vbulletin forums are now Xenforo boards.