For a PhD interview (European paid PhD which requires a MSc), what is the best way to present personal and health issues when motivating a bad grade? To put it in perspective, I have overall good grades from more than 30 courses, but I have two relevant courses taken 2-3 years ago (at the same time) where I just got a pass. These courses were only graded on the basis of one exam each, so the grade only reflects my score on the exam. The poor grade was due to a combination of mental health issues and a very stressful family situation, which made me completely lose focus while writing the exams.
How can I present this is a polite way, explaining that it doesn't reflect my actual capabilities? It was also more than 2 years ago, thus I've amassed more knowledge within these topics. It is quite common for course grades to be based on total effort, but for these I only had a few hours each to prove myself, and in a bad condition. I have also shown that I understand the topics through other courses and the theses I've written.
Are interviewers usually understanding in this regard? Especially, since it was a few hours of exam time, taken place 2 years ago while feeling very unwell, it is a very minor issue. Other than this I have a very good record, but I fear that this will come up as a question since it seems very out of place.