This is what I do.
First thing I think of is, what could I do to
disrupt my immune system.....ie.
Coffee
Sugary snack
Don't do that.
Sleep sound....herbal teas and melatonin helps when there's trouble sleeping.... chamomile, hops, passion flower, vallarian.
Plenty of Pure water and herbal teas, but nothing else.
Vitamin C to bowel tolerance.
Some recommend zinc, but most forms must be given with a meal with some food already on the stomach. Otherwise an upset stomach can result.
D3
Garlic
If there are immune supporting herbs available, some find benefits from astragalus root tea, echinacea, cat's claw, and to settle any stomach distress fresh ginger root tea.
When I implement a combination of some of these at onset of symptoms, the cold or flu is usually cured. I don't do doctors for treatments. I would likely be given an antibiotic to "cure" a virus; which btw, they can not do. I won't say what you/ she should do, but I don't. I never saw the benefits, just risks.
After it's been established for a day, it normally runs the course, but the symptoms are lessened and duration shorter. I can't recommend anything specific for her as she might be on a blood thinner and have specific needs, etc.
Even garlic is a mild anticoagulant. Certain meds for heart conditions, for instance, might be keeping a range that the natural (normally safe) herbs might change. Just something to keep in mind. As congestion occurs, I don't take anything to dry it up. It's the body's way to get rid of the viral load and toxins. Water helps it loosen up and helps cell transport. Dairy is avoided since it tends to thicken phlegm. It's hard to go wrong with water.
Hope she feels better soon.
HC