Girlfriend needs the cheapest PC upgrade for Monster Hunter Wilds on 45-60fps on 1080p

We really want to play together, since MH World was the first game we played together. But are kinda poor currently. So we can't afford anything but mid tier components.

Her current setup is:

Ryzen 5 2600

Gtx 1070

16GB RAM (no idea which, but it's fast enough)

500gb SSD

1,5GB HDD

In the benchmark she gets around 24 FPS in lowest and medium. I that's because the CPU is just too weak right?

Should I just buy her a Ryzen 5 5600x and could that be enough?

Edit: I appreciate all the financial advise. We both are doing our master thesis and reduced our working hours to a absolute minimum and live from intentionally safed up money. So worst case is we have to increase working hours again and have less time to play MHW, not die of hunger.