No, absolutely not. If you had ignored it, she would have assumed she had gotten by with it–and would be much more likely to do it again.
The real issue is why she did this–and the answer could be very serious. Is she experimenting with drugs? Is she even in danger of becoming addicted to some types of drugs (such as strong painkillers)? Or was she hoping to sell these drugs to others? The issue isn't simply that she stole from you, but that she may well be involved in something much more serious–and destructive.
You love your granddaughter–and because you love her, you want what's best for her. This is why I encourage you to confront her and find out the real reason for her theft. Then urge her to face the dangers of drugs–and turn from them. The Bible says, "The tongue of the wise brings healing" (Proverbs 12:18). Her parents also need to be aware of this, because the dangers are simply too great.
Most of all, pray for her, and urge her to turn to Christ. She needs His strength to resist temptations and pressures, and she needs His guidance for the future. God loves her, and Christ wants to live within her and help her do what is right. The most important thing you can do for her is to point her to Jesus.