Don't keep saying she's brave, resilient etc. She's getting through a shit situation, she's not a superhero. Saying that kind of thing is basically like saying 'I'm not going to think too hard about what it's like to be you, because that would never happen to me.'
I've not had a child die, but my son was critically ill for a while last year and spent a fortnight in hospital then recuperating for a few weeks more. What helped was having people available to talk at, at any time. Practical things like childcare and bringing comfy clean clothes and toiletries. What didn't help was people making sad faces and asking for updates all the time.
There was also lots of practical stuff that lapsed - insurance renewal, paying bills, cleaning the house, watering plants, emptying the bins etc. For a while we basically only came home to sleep so everything went to pot a bit. If you can help with any of the mundane stuff without her having to fill her head with it, that would help.
One thing I realised when my son was ill, you just can't run on maximum distress all the time - even when things look fully bleak, there's a limit to how much of the day you can spend wailing. When her child has passed away, she might be glad of just having someone to go for a walk with, watch boxsets with, without having to feel guilty about wanting to do mindless things in between bouts of grief.