Lovely words about your mum OP.
i'm mid thirties but mostly housebound with health issues, particularly at the moment as am recovering from a real dip in health and some things I've really appreciated or have just purchased myself and love:
Good quality fluffy electric throw blanket - so lovely for keeping cosy but also useful for pain.
New pillows/duvet or a back support cushion ( lots on amazon)
Aromatherapy diffuser or nice candles
Kindle
Some lovely Bookmarks (etsy is good for these)
New mug/tea & coffee bits and pieces such as syrups
Instant hot water machine if the kettle is something she struggles with.
Epsom Salts for the bath (which can be good for certain types of pain)
A neck pillow or infinity pillow, similarly a body support pillow for bed.
Postal gifts or subscriptions for cakes/brownies throughout the year, or vouchers for COOK where you can choose your own (nice) ready meals that come frozen.
Puzzle books
Comfy loungewear or new dressing gown
Monthly flower subscription (eg Freddies Flowers)
You don't say (and don't need to say) the nature of the illness but there might be other specific things that can make her more comfortable so I'd recommend looking on illness specific forums or on charity websites for her illness to see what they recommend.