Important files and photos saved on Cloud service What happens if the iCloud/GoogleDrive/DropBox data center where my important files (business info, family photos) are saved ever faces a catastrophic situation like a terrorist nuclear bomb attack? Is my cloud data stored in more than one geo-location?
Yes, your data is stored in multiple different locations. Most of the time cloud services has various datacenters in multiple countries on different continents. 

As user you don't know where your data is stored exactly and how many copies of that data is stored. But you can bet they have a backup of a backup of a backup. 

Because systems, servers, harddrives fail every single day their systems are designed to keep all the data save.

Keep in mind companies can decide to stop offering cloud services. So if you are a little bit smart, you have backups as well.