Hi and welcome.
FLu is usually self limiting and all she needs to do is drink enough fluids and rest.
 However some remedies may also help and  flu treatment you should take depends on your symptoms. For example, if you have nasal or 
sinus congestion, then a decongestant can be helpful.
Decongestants come in oral or 
nasal spray forms. Decongestants are used to reduce swelling in the nasal passageways. However, nasal spray decongestants should not be used for more than a few days because, if they are used too long and then stopped, they can cause rebound symptoms.
If you have a runny nose, postnasal drip, or itchy, watery eyes -- then an antihistamine may be helpful for your flu symptoms. Antihistamines block the effect of "histamine," and help relieve such annoying symptoms as 
sneezing, itching, and nasal discharge.