It is likely this hard candy will be broken down in her stomach by the stomach acid, but the sugar from it may give her a tummy ache. I would check the ingredients of the hard candy to make sure there is no xylitol in it. That's because xylitol is highly toxic to dogs, and if it does have that ingredient, she will need to see a vet immediately. Xylitol ingestion can be fatal. Otherwise, she should be fine aside from the chance of GI upset in the form of vomiting and/or diarrhea. Should you see that, withhold food for 12-24 hours, then feed a bland diet of boiled white meat chicken (no bones) and white rice in small amounts several times a day for a couple of days. Then slowly add back in her normal diet.