Wifi 6e is the most current available technology - in addition to the 2.4 and 5 ghz band, 6e offers 6 ghz band as well. I would suggest getting at least a wifi 6 router.
I currently have this one - had it for a couple years and it has been great - and it's only $50: https://www.amazon.com/NETGEAR-4-Stream-AX1800-Router-RAX20/dp/B07Z5JWRWJ?th=1
I have a 2,500 sf house (1st level) with a basement and get coverage in the entire house, but ymmv. I do have 1gb fiber internet - so a drop in speed with distance from router isn't an issue. If that is an issue, you may want to look at a mesh option. However, if the house is wired for coax and all the runs of cable aren't needed, then hard-wiring a second router in AP mode using a moca adapter will still likely get your better results. Here is an example of a moca: https://www.amazon.com/Hitron-Ethernet-existing-Backbone-Streaming/dp/B08MQG6T61
Is she needing a cable modem or will that be provided by the cable company? If it is being provided, then will it will come with a wifi router as well?
Seems the TP-Link Archer AX55 (AX3000) ~$110 and ASUS RT-AX86S (AX5700) ~$160 both generally get positive reviews.
If they value support & warranty length I think TP-Link is one of the few left w/2yr.
Some manufacturers are down to 90 days of "free support".
The latest standards are all about better handling of multiple devices fighting for the same signal as well as helping devices avoid battery drain.
So makes a lot of sense for tech heavy households.
I run a wired AC mesh with 3 nodes and turned my old N Asus router into an access point. My and my wife's office have wired connections for computers and printers and I also have a wired connection for the streaming box. So I get the full 1GB internet speed as well as no interference at the devices that consume the most data. I have actually set all wireless channels to their narrowest width which limits their speed to 0.1GB. This results in a stronger signal and is fast enough for all the devices that are wireless.
I actually used a single Asus N router for a long time but as I started to add more IoT devices, including cameras, I needed more processing power and better reach.
I've found many an older router a good home in a senior person's home / apartment where all they do is check email, maybe use WhatsApp or similar to speak with overseas relatives and have a digital photo frame or two. Occasionally stream a show on a Roku (if a younger person is there to start it for them). Most of this not simultaneously.
Now, when all the grands and/or great grands pile in, well as one of the elders said, "who cares, they're here to see me and their cousins not have their faces buried in devices".
I'm a fan of the Belkin AX3200 / RT3200 / Linksys E8450 as of...well, when I bought mine. That's partly because it does well with openwrt, and all I know about the stock firmware is I don't remember reading horrible things.
Unfortunately it looks like Amazon is currently only selling the Netgear version for $98 despite Wal-mart apparently having the Belkin for $50. I didn't look into it in as much detail as I might have, though. I ordered directly from Belkin and couldn't find the Belkin product page in a quick poke around the site, only a support page.