just seen update, Covid won’t help appetite obviously, especially if she already has respiratory issues.
can you talk with mum privately , in person ideally, or on video call? Can you ask her bluntly if she acknowledges if she doesn’t drink she will die and is that what she wants? It’s hard to ask, obviously phrase it gently. Not as a “ you do realise” but a “ is this deliberate, is this what you want?”
if it is VSED, in that she just wants to die, then you are going to struggle unless she agrees to some intervention regarding her mental state, and some reassurance her quality of life can improve, how that’ll be achieved. If she’s set on VSED then that’s getting her support, palliative care to manage any discomfort…but without an underlying condition, I’m not sure how nhs supports as she’s essentially going a suicide route.
if it’s not VSED, and she’s genuinely just can’t face food or drink, then the question is why, and it’s all the family pushing to get investigated…something must be going on…she’s not old, old at 79. Not if, other than breathing, she’s seems in reasonable health.
.what I will say is the elderly, especially when not mobile can exist for long time on very few calories. My dad stopped eating ( he was on EOL though ) for 9 months before he died. He’d have Something for a day or 2 here or there when he’d fancy something, but most of time was barely having a mouthful, and 3 days or so of nothing at all. He also didn’t drink much at all…sometimes a quarter of a cup of fluid all day. I was shocked at how long he lived on so little food and drink. So many other posters saying same thing. But, he was on eol, and his body was shutting down anyway. If there’s no terminal condition underlying, it wouldn’t seem normal.
not impressed by nurses getting frustrated…no matter the reason, she needs support not impatience! I’m surprised by that.