I wish you and your mother well.
Pneumonia can just creep up on you without you realising it.
I had it back in 1990 and had a week in hospital on strong antibiotics. I went off of food and only drank fruit squash drinks. I lost over a sone in weight.
She is back home, but very weak. I think that she is too ill to be at home (on her own) but not ill enough to need a hospital bed. I can understand that with limited resources, sometimes the NHS has to make difficult decisions. I am hoping that if my Mother is at home, it would mean there is a bed available for someone much younger, as in your case in 1990. I know that my Mother prefers to be at home.
The problems arose yesterday because they prevaricated over whether she had been admitted, and they did not know where she was. Although her care package had been temporarally suspended, the hospital would not re-instate the care package, because she had not been admitted. The carers would not reinstate the care package because she had been admitted.

Fortunately the emergency dept of Social Services eventually intervened.