That narrows things down enough.
You're looking at an ordinary Blu-ray player. Any of the major manufacturers (Sony, Panasonic, Samsung, LG) will do just fine. My preference is Panasonic.
Here's a simple to use BD player that will also play UK DVDs.
Panasonic-DMP-BD84EB It's under £60.
Here's the same player buy made multi-region* for DVDs if required.
Panasonic-DMP-BD84-MultiRegion-DVD It's under £80
You will need to buy a HDMI cable to go with it. This is the same for most BD players now. Here's an
Amazon Basic 1.8m for £5.99
*
Multi-region DVD. If you're not already familiar with the term then the chances are that this isn't an important requirement for you/her. However, if you'd like to know more, then here's a quick primer: The world is split into sections (regions) so that the film studios and local censor boards can exert some control over who sees what and when. Or at least that was the original idea when DVD launched in the late 90s. The UK, Europe and the Middle East is one region (R2). The N. America is another region (R1). Here's a link to a
map showing the rest of the regions.
There used to be a time advantage buying films on DVD from the US. They'd be released there about 6 months ahead of the UK. That doesn't happen so much now. They tend to launch at roughly the same time give or take a few weeks. The other incentive for buying films from outside the region 2 zone was special editions not available here. With the shift from DVD to Blu-ray, and now Blu-ray to UHD discs for serious collectors, there's probably not so much interest any more in importing special edition DVDs.
One area where there's still a requirement is home movies transferred to DVD. For someone who has relatives in the US an either isn't able to- or can't do anything with a file transfer over the internet, then a DVD sent from the US to the UK is one way to share family memories. Such a disc could be made region free (plays on any machine) but might equally be recorded with Region 1 encoding which would make it unplayable on a normal Region 2 locked UK BD player.