Aww OP. Words of wisdom? From experience of a close friend who got a 3rd and was gutted. Lots of tlc, if you’re off or can get an early finish/ day off, see if you can take her out for a walk, a coffee at her favourite cafe, the cinema, anything to take her mind off.
She is going to be really sad and will be analysing what went wrong so might need a bit of space to wallow and be upset. If she’s not up to going out, favourite drinks/snacks and/or movies or activities might help.
Also, lots of support and reassurance from you. See if you can help your DD reframe the situation. Instead of her thinking she’s done terribly, what she has done is achieve a degree despite it being a struggle. She could have dropped out but she persevered. Those are qualities that future employers will value.
My friend got a third and is now in a highly successful career. A degree shows you can study and understand things at a higher level. They are very useful to have but are most definitely not the be all and end all.
A talk with her tutor/s may help once she’s had time to process the disappointment and had the result breakdown. If there is anything she feels is grossly unfair maybe she can challenge it appropriately but if it all looks to be fair feedback and she has a third, she still has a degree.
I can honestly say that I and my friend have only ever been asked to demonstrate we have a degree, I’ve never been asked the degree class.
There are so many expectations set regarding going to uni and having to get a 2:1 or a 1st to be successful but it it not the case.
I really hope she is feeling better soon.