If anyone else's DC is in the same situation, please share any guidance they've been given by their university
As Errol says, each university will be offering their own guidance. She needs to be patient.
I'm in daily touch online with my dissertation students either by email or on our remote face to face platform. But I'm also getting a lot of emails from students saying "Oh I don't read my emails." 
Please ensure she has read her university emails and understands arrangements. Or that she goes to her university website and looks for "Corona virus" arrangements. It should be everywhere on her university's web pages.
At my place, we have put in unprecedented arrangements for extensions, mitigations, and deferrals, as well as a "no detriment" policy for assessments after a particular date. But not all places will be doing this.
The main difficulty I have found is students simply not reading my emails or not paying attention.
If she's currently unwell, then she needs to flag that up in the usual way. Again, our students do a self-certification form, and for the last few years that has been electronic. So she should do this in whatever way is usual for her institution. There will be standard guidance in her student handbook.
(Again, my frustration is that my students don't take any notice of all the ways we offer for information & support!)
Hope she feels better soon.