I think the mother and the student have definitely failed. That said, the school is producing many such failures. At some point blame needs to transcend individuals and start attaching to the system or context those individuals are in.
The real systemic issue is that nearly ever competent and rational actor is incentivized to run away from the problem. This applies to parents, teachers and administrators. No one's life gets better by taking this problem head on and making things incrementally better, so the only people who are left to deal with the problem are the ones who don't realize how bad things are, don't care or don't have the means to move away.
We're not anywhere near that point. Half the people here place no responsibility on the parent. At all.
So maybe we should actually try this 'individual responsibility' thing before blaming the system, or aliens, or the Illuminati.
This is even more true, I think, when it is not a single teacher whose class is failing but a school's, and, I expect, a large part of that school system is failing. We should investigate and understand why and a satisfactory answer is not that one particular mother and child were derelict.