Hi Brenda, 

Unfortunately if the redbud didn't leaf out or flower last year and seeing the borer holes on the trunk, it is most likely dead and should be removed. If it is very tall and not something you feel is manageable for removal, we would recommend a certified arborist to assist with this. 

We are not sure exactly the cause of decline and often when insects infect a tree or plant it is a secondary response due to another stressor the plant is suffering from. Insects can sense the trees stress pheromones and then take advantage of that. We can't say for sure that it was ambrosia beetle or another bark beetle but an article from Ohio State speaks about this process and you can read that for more information. It looks like the soil around the base of the tree is compacted and possibly lacking organic matter so the tree could have been failing due to that. Trees benefit from mulch or leaf litter at their base and typically out to drip line of the branches (where the branches extend out to) and while this isn't usually that applicable in a small yard setting, making sure they have organic matter feeding the soil composition at least 2-3 feet out from the trunk helps trees to thrive and live longer in urban and suburb settings. Mulch or other organic material helps to retain soil moisture and keeps the roots cool in the heat of the summer. 

If and when you choose to replace the tree, be sure to mix in some soil amendments of compost and or some topsoil to add nutrients back into the planting area. 

Emily 

sorry for the sad news and you're welcome