hmmm, irises can survive winter. Why are you digging them up?

I have to dig mine up here in zone 5 and wait until a frost has blackened the leaves. Then I cut the stalk all the way down and dig up the rhizomes. I hose the dirt off and store them in a box in my basement until spring. You can transplant yours into the ground at the point or store them.

Yes. No need to dig up the iris (unless mom is just giving you some).

I do the same as daisy with my canna - but I see you are zone 7. If you have to dig them from your moms, it may be worth noting if they have been hardy where she had them. Some are hardy to 7, and depending on location and mulching, etc, many that are zone 8 will be OK in zone 7 too. I'm wondering if you could just dig them with the root and put them in the new location now (and not store them). We have several TX canna people here and I'm sure they might want to chime in on this. Maybe if your mom is done and in no rush - assuming they are hardy to that location - you could just leave them, clean up the foliage for her once it browns, and then transplant them in spring?
Good luck.