If generic, she might be able to get it filled at one of the places offering $4 scripts. If brand-name, patient assistance programs run by manufacturers may help. Check with doctor before switching from brand-name to a generic.
If the pharmacy she uses is in the network,
Free Drug Card - Discount Drug Card - Prescription Drug Card - Prescription Assistance might lower her cost. I get my Armour Thyroid, 100 pills for the price I was paying for 30. You have to buy in specific minimum quantities to get the discount.
There is information about patient assistance programs here:
Patient Assistance Programs - Prescription Drugs for the Uninsured
Finally, is she low-income uninsured? Many states have Primary or Physicians Care cards that provide basic care through the Health Department or a doctor that accepts the PC card. It includes a co-pay pharmacy card. You can usually apply at the Health Dept or Social Services. This is a program for those who don't qualify for Medicaid, which many don't.