It's time to re-pot it in something wider (but not necessarily deeper - these don't put out many roots). Wait til the top soil is dry next and yank the whole thing out. Gently separate the rhizomes. Each one is its own individual plant. Give one to your dad. Toss out the dying part and make note if the rhizome was rotting. If the soil down there is still wet then you're watering too often for this plant or it has poor drainage. Nurseries often don't clean out material used in propagation so remove any rockwool or similar material and add some perlite and/or sand and mix it in to the remaining soil. Or ideally replace the soil entirely with a succulent potting mix. This plant can handle a lot of abuse. When you re-pot in the new soil you get to arrange the rhizomes however you want and can create something that looks entirely new. Just give the rhizomes a bit of distance from each other so they have room to breathe and grow.