There is no such thing in our knowledge that covers for prescription drugs replacement. You have two options in case your mother needs additional medication while in the US: 1. If you want to get the medicines in the US, you must get a prescription written by a US physician. You may not get the exact same medicine, but you may get an equivalent substitute. 2. You may get your medicine from your home country via mail/courier as long as it is in limited quantities, and is not a controlled drug. How would you get medicines from your home country? Someone from your home country can mail it. Keep a copy of your prescription from the doctor, copy of the pasport page of the person (visitor in the US), and a letter stating why this medicine in being sent. The courier /mail service provider may ask for any additional documents if requested by customs.
Insurance rates are regulated by law. You can't find the same insurance plan for a lower price anywhere else