Cameron,

Tough situation for you. She's your Mom, so doing nothing is not an option for you. But IMHO you're putting too technical a package together for her; I believe the small steps others suggested might be more productive. Anyway, back to your question:

That ruck is too way big and technical. Stick to something very simple and smaller - like a small duffel with handles and a strap. Perhaps look at dry sacks that folks use canoeing - check out what folks use up in the Boundary waters where they not only canoe, but portage frequently.

If you truly insist on getting her a ruck, make it a LOT smaller and simpler. Torso length? Anyway you can actually fit her? After all, she's in the Seattle area; plenty of shops - you could pick one that's convenient for her and call ahead to make a fitting appointment for her. Perhaps you could join REI? I usually dealt with friendly and reasonably knowledgable store folks at REI when we lived in that area.

It rarely gets very cold there. A couple of blankets or comforters are a lot more familiar than a sleeping bag. I suggest a full size fleece blanket (fabric store; cut to size and you're done - no sewing skills required) and a regular sized comforter. Toss in full size Z-rest if you insist, but odds are she'll find something besides the ground to crash on.

Forget a bivy, tent, or fancy tarp - again, too complex. There's just nothing you can do about this if she is on her own. She will probably have some sort of shelter anyway, even if it's just her vehicle or a damaged building. If you absolutely feel you have to do something, I suppose a small tarp won't hurt; she can at least wrap it around herself. Just about anything will do - 6 mil plastic sheeting, expensive coated nylon, even more expensive sil-nylon, or my current favorite, a square sheet of Tyvek house wrap (soften it with the cold-wash in an top loading washing machine - that really works). You can write a LOT of potentially useful info on the Tyvek with a permanent marker (starting with "THIS SIDE OUT". Roll up the blanket and comforter in the tarp and you've already made a physical statement on how to use it... secure the bundle with a couple of adjustable straps with Fastex quick-release fasteners or for an even simpler solution, a couple of elastic bungee cords (anyone can figure those out).

The rain gear is OK. Add a brimmed rain hat with tether.

Add 1-2 pr comfortable liner socks (silky smooth texture - shop to find) and 1-2 pr smartwool socks in her sizes, then add light weight and comfy walking shoes that fit over those - can be as simple as good athletic footwear or a as fancy as your wallet can stand, but I'd stick with woman's cross trainers, running shoes, etc - she's more likely to put those on.

Too much food and water plus the food probably won't get used. Find some energy bars she doesn't gag on in non-stressful times and put two per ziplock style bag - 9 would be more than enough to provide a little mental comfort if she needed them. If you want to spend the money, the filter you suggested is as fancy as she is likely to be able to use. Toss in an empty polycarbonate 1 L wide-mouth Nalgene in a slingable bottle carrier because she will understand not to throw that away. Basic water should be simple, like a small case of 16 oz water from the grocery store - call her once a year to cajole and remind her to replace it.

Flashlights? Get something LED that runs forever on 1, 2, or 3 AA cells and then stock her 2 sets of lithium AA cells (go ahead and risk keeping one set in the torch). Or get something that uses CR 123 cells knowing that she probably won't be able to scrounge replacements. But stock her with lithiums, whatever the size. And get something small and simple for her keyring, like a white Photon.

If she might need personal hygene products, include them (for all I know, she's younger than me). Heck, include them anyway - she might be able to help out another woman in need. Regardless, for sure include TP!!! Regular stuff in a ziplock is more likely to be found, recognized, and utilized than anything fancier. Add a sealed foil travel pack of baby butt wipes inside another ziplock - get good ones, unscented if at all possible. They also are fair for wiping off dirty hands and faces.

A pair of 3M N95 face masks with valves. Leave them in the blister pack (easy to find and understand purpose) and put that inside another (large) ziplock. Also dust goggles - if nothing else, ski goggles with clear lens (amber second choice).

A roll of duct tape inside another ziplock (heck, anyone can figure out things to use it for).

A good set of ladies leather gloves that fit her properly. Better, one pr of those (Thinsulate and leather) and one pair of properly sized thin and flexible leather work gloves, like deerskin - something obviously "work gloves" but "fit for a lady". Ziplocks again.

Already probably up to more stuff than she will like, so I'll quit. Oh, not quite - MAPS - ziplocks again - Stick a Thomas in and then add whatever regular maps you think she might be able to read and understand. That probably means no topos unless you get the type that have relief shading added (hard to get in the US). I guess it wouldn't hurt to add a simple compass just so she can figure out which way is North, but you have to deal with a LOT of declination in that area... I dunno if anyone makes a dummy compass that is corrected for local declination (they ought to - gee, a product idea).

I quit here. HTH

Tom