Mostly they give Tarceva after you finish chemo (and radiation, if you need that too); like a maintenance drug.
Most important, though, is a positive attitude. You really, really, really have to fire that doctor!! That is going to be a pivotal factor in your mom's survival!
As I read, it seems to me that there is one statistical marker for long term survivors - they fired their first doctor! It can be unpleasant to fight with a doctor, but it has to be done. If a doctor won't talk to relatives and caregivers, gives you attitude about a second opinion, and won't answer questions (my brother's first doctor refused to spell the names of drugs or medical terms; he told me not to look things up on the internet!), that doctor is not a competent clinical oncologist.
The current wisdom is that you must treat for the psychological aspects of the disease: the doctor is the coordinator of the "treatment team" which includes relatives, friends, and any support the patient can marshall! When I had my breast cancer scare, the nurses told me to round up a posse, and never go to an appointment alone!