ANSWER:

He must pray on time as such fears are not real and we can’t simply abandon prayers for such a reason. He can combine prayers as prescribed. 

My aged father (69) plans to make an 18 hour train journey alone, Delhi to Bihar (India) and back. Can we (his family) advise him to delay prayer and not to pray in public place as we fear for his life because Hindu mobs are forming left and right if they get triggered by any small thing such as a Muslim’s prayer and a single man does not stand a chance to such bruteless mobs.