Instead of leaving India entirely, perhaps it might be good idea for Muslims to move to Muslim-majority areas inside India? That way you will not be spread too thin to defend yourselves. I have some distant family there, they have told me that Muslims have no issues in Muslim-dominated areas.
Also, you can increase your reproduction rates - i.e, have more children - as encouraged by Qur'an & Hadith. Muslims should go back to the Qur'an:
Sahih International: Your wives are a place of sowing of seed for you, so come to your place of cultivation however you wish and
put forth [righteousness] for yourselves. And fear Allah and know that you will meet Him. And give good tidings to the believers. (
https://quran.com/2/223)