Do I have to take these resits and is this mark taken if lower?

Hello
I am in my first year at uni and it's been a nightmare so far. I gave birth to my daughter back in January who was born with a rare condition and has been very sick leading me to not do as well as I had hoped but I'm still wanting to continue with it.

In 3 units I received the following:
Assignment: 72%
Exam: 35%

Assignment:69%
Exam:15%

Assignment:81%
Exam: 36%

I have passed all my assignments but got lower than 40% in my exams so I have referred for a resit on Monday. However, I'm currently in an out of the region hospital with my daughter and it's going to be hard and expensive to get back to uni and I do not want to leave my daughter.

Do I have to resit these? Considering combined with the assignment grades I already have a total of over 40% therefore a pass? Or do I have to pass the exam in its own right?

Also does anyone know, if I was to retake the exams and get lower than my original mark, will they use the new mark or the old and better one?

On my results page it used to have my grades from my exams but now they've disappeared leading me to think they're irrelevant and the new grade will be the one counting even if it's worse...

I'm just so stressed and not what I need right now but uni doesn't open till Monday so can't ask questions till then and that's when my first exam is scheduled!

Okay Thankyou. But in the event that I do not need to pass the exam to pass the unit, will they take the new grade or refer back to the better one?