Welcome to Healthcare magic forum.
The lump you noticed is most probably a palpable lymph
node swelling which are commonly seen in case of infections.
These lymph nodes are sites of storage of immune cells i.e white blood cells and they get swollen due to overfunctioning to fight an infection.Since her right ear is infected and her right preauricular lymph node is palpable, it's most likely related to the infection and not a malignant lymph node swelling.
In case of tumours, the patient has history of long standing mass or swelling which gradually increases in size , is usually painless and associated with generalised weight loss
,long standing fever
So dont worry, once her infection is treated with appropriate antibiotics course, her lymph nodes wil disappear or become impalpable in few weeks.
Do ensure she has plenty of water and a nutritious diet for faster recovery.
Wishing her a speedy recovery.