I have lifting hooks and lifting straps.
The hooks were just for extended hangs from a pullup bar, but they do work for deadlifts. It's something of a weird feeling, and they're kind of a pain to actually use, but the grip is completely out of the equation.
The Harbinger lifting hooks, blue hooks, have a padded wrist wrap, and they cinch down tight. The weight is distributed pretty evenly, so you're not getting any real pressure points as you would with most straps.
As far as safety, there's enough mechanical friction around the wrist and the hooks are plenty strong. I trust them at least into the upper 300lb range, which I'm guessing she's not working with.
If you need to completely avoid any grip at all (you can still put your fingers around the bar though), I would suggest those. They take some time to put on and remove since you need to make sure the bar is snug in both hooks on each hand, and vice versa for unhooking them. Assuming she's controlling the eccentric, this shouldn't be an issue other than time.
If some grip is ok, then there's also the "Harbinger Big Grip Pro" lifting straps. They have a rubberized coating on the straps themselves, and are padded around the wrist in the same way. You can get some weird calluses, but basically they're designed to give you as much mechanical advantage grip-wise while still being straps.
(I own and have used both.)
As far as just general hand/wrist stuff, depending on the issue, I'd also look into doing a few sets of finger extensions with a rubber band throughout the day.