4 year old temper tantrums

[Amy844]

I'm 66years old, watch my 4 year old granddaughter 4 days a week, 10 hours a day. Her mother has her for 5 days, father 5 days. The child has no rules at the mothers, she lets her do what ever she wants. The mother has 3 other children, ages,16,14,11. They teach her really bad words and behavior. The 14 yr. old is a girl and has to watch the child at all times. The mother thinks only of herself, goes to school at night, leaves the kids home at all times. The father can control the 4yr old when he has her. I've tried talking to the mother, she blows me off, pays no attention at all. I try to give the child structure, like meals, naps, reading, playing, taking her to the park, doing all I can for her. The problem is, the child has told me she hates me, runs away from me, screams, I've tried putting her in the corner, talking to her, yelling at her, nothing works, I'm going crazy, and feel like I've failed. What can I do, please help, I'm desperate.