You are probably not going to make much headway against this lady. If I were to try I'd point out that her comment above is a weakness. The Bill of Rights are all equally old. I might try to point out her rights to free speech, assembly, to remain secure in her papers and possessions, to practice her religion of preference, are all protected by amendments that are just as old as the second, and would she be so dismissive of those rights based on an argument of age? She's either cherry-picking or she would agree the other rights are just as suspect as she views the right to keep and bear arms.
It is always amazing and saddening to me to see how many people are not only willing to see our Constitutional rights eroded, but are in fact anxious to see them gone.
Scary. Very very scary, indeed.