Amma told Radhika to save her father, Radhika is running to the place where her father will drown, how does she know where it's happening, she didn't give instructions to Dev, so did he know, if he did know, why was driving around knowing that Radhika's father is going to kill himself?
Also another thing, Amma departed a few minutes after Radhika, so how did she get to the area before Radhika, if she took some sort of transportation, shouldn't she have taken Radhika with her, instead of letting her run all the way? Especailly when Amma wants to save her son