My holly bush is dying. Leaves are falling off.
Start by checking for common diseases: https://www.gardeningknowhow.com/ornamental/shrubs/holly/diseases-of-holly-bushes-pests-and-diseases-damaging-holly-bushes.htm
If you can eliminate these kinds of problems, chances are that the hard winter is what is causing your plant to lose leaves. Bend the branches to see if they are still alive; they will be flexible if they are, they will be crisp and snap in two if the branch is dead. You can cut off dead parts, and sit tight and hope for the best. Practice good care for your bushes, they will come back if they can. Here is an article on caring for hollies: https://www.gardeningknowhow.com/ornamental/shrubs/holly/growing-holly-bushes.htm