Harsh, maybe you can pull the daughter aside and talk to her about your wife's reluctance. See if she can talk your wife into riding with her or joining you three. Will she ride double with you?
The wreck certainly will make one recognize how much a spill can do. A pair of Joe Rocket Mesh (Ion I think isthe name) pants can give you some CE rated hip and knee protection as well as road rash protection and can be worn over street clothes or even shorts. Road trash is really nasty to heal from.
I had a bicycle wreck when I was around 10 where I went over the handlebars and road rashed my arm, stomach ( no shirt) , knees, heels of palms, etc on asphalt. So, I know how even a short slide does to flesh. So, while not great gear, it is good gear for the money.
I would recommend that to help her mindbe put at easefor scars ifs she does take a tumble.
Get her a top case and a rack that won't look awful with the bike and she can lock the gear up when off the bike. If large enough it can fit boots and pants and jacket and a seat lock helmet lock can be fitted to the rack and case mount to lock the helmet up as well. If the helmet/seat lock were deleted with her bike's build. A locksmith can rekey it to the ignition if she doesn't want multiple keys if she starts using it.
Just some thoughts on things which might make her hesistant to use or learn to ride. A scooter like a Honda C70 or a Sym Symba (used) is a great scooter that is not too expensive and very friendly with their auto clutch. The Sym products are very good as they made motor parts and other components for Honda's bikes for 15-20 years before building their own bikes and motors. So, they have a good history of building parts that last and are good quality. The Symba came out before Honda came out with their Super Cub design to celebrate the anniversary, so it is very much like the Cub 50 cc model but it has a 90cc motor capable of doing 55-60 and it has the improved brakes to handle stopping very well.
You are likely to get out of it what you paid if well kept and you find a decent price on one.
She then can overcome the fear that might be there with the death grip. The C70 is easy to work on but often have neutral switch issues requiring kick starting. It can be easily kick started with one or two kickstarts and you can even start them with your arm/hand being a low compression bike. The Michelle Gazzelles are great wet dry tires for them too.
David