I understand your frustration but I don't see that speaking to him will make any difference. It hasn't so far, and why you think that continuing to try that route will be successful is beyond me. The child is 2 and the father hasn't stepped up.
Besides that, it's not your job. It's your frustration to keep bailing her out, but his parenting (or lack of it) is not your concern.
I read your prior posts and there seemed to be a theme that your daughter was unprepared in many ways for adulthood and parenting. But again, the child is 2. The mom needs to step up and not be bailed out all the time by grandmothers. One grandmother is already having them live in her home, right? Cancelling plans all the time isn't sustainable and it builds bitterness and frustration.
One thing I'll take issue with is your statement that the father "will get what's needed at times." That's not enough, and he has a legal responsibility to support his child, not pick up a box of diapers now and then or whatever. Your daughter needs to get court-ordered child support. If he doesn't want to cooperate, too bad - the court will take it out of his paycheck. If he doesn't have a job, he can explain to the court why not. So, I'd urge the mom to get some parenting classes and to insist that the father get them as well (through the court) - I don't see why leaving a 2 year old with a disconnected and ill-prepared bio father is advisable. Which is probably why the grandmothers are stepping up so much. Perhaps the mom could benefit from some life coaching too, to help her with confidence, focus and direction. Continuing to enable her is not good for anyone.