OK, that makes it easier to make suggestions. Sorry to hear about your situation and your Mum and how it's affecting you all.
Is she getting specialist treatment for her kidney failure and diabetes? From doctors and specialist nurses for both conditions, perhaps in a combined centre / clinic? If not, she should ask her GP to refer her.
If she's falling regularly, she should ask GP for referral to a falls team - these consist of doctors, nurses, physios, occupational therapists etc; treatment includes aspects such as reviewing medication, adjustng if necessary, recommending changes such as improved lighting on stairs, use of walking aids etc; depending on her housing situation, adjustments might be made for her. Even if there's no falls team, is she getting specalist care from surgeon and hysio for her torn tendons?
As she's obviously getting frustrated, perhaps even clinically depressed by her change of circumstances, and especially as waiting lists are long, she could also ask GP about referral for counselling.
As you say she gets frustrated that all conversations are about her health, then you'll have to provide some non medical chats - almost certainly, she wants to be a mother / grandmother first and have diabetes second, and I can understand that. I find I can help my family more by giving practical help, sometimes even distractions, when they have health problems, and they know better than to hassle me about my health!
If her health situation is long standing (for at least 3 months already and likely to last for at least 6 months longer) and she needs help from another person and / or has difficulty getting around, then she could apply for Disability Living Allowance, both care and mobility components. It's well worth getting advice from CAB or local welfare rights centre, as forms are very complex and the general public, for obvious reasons, doesn't know what details are important.
