Your GP is the first port of call, although you could also call in the CPN if you have one. It's quite likely that the GP will be able to prescribe something to help right away, but may also arrange for mum to see a specialist psychiatrist who will decide on longer term treatment.
There are quite a few things they have in the cupboard for agression, depends on the severity and frequency I guess.
My dad was prescribed Quitiapine because he had started to become agressive, mostly verbally but it was escalating - but he also had (and has) terrible paranoid delusions and the drug is supposed to help with that too.
I don't think sectioning is likely, that is usually a last resort, to be used when everything else has been tried and failed or in an emergency when the patient is at immediate risk to themselves or others.
A GP cannot normally section someone on their own, unless they deem it an emergency. It usually takes two doctors in agreement (normally, one will be the patients GP, the other a psychiatrist) plus either a social worker or the patient's closest relative.
They may recommend a short stay in hospital whilst mum's condition is assessed and a course of treatment decided.
Of course, things like this are horrible, but if mum is becoming violent, then it may be the only choice for the sake of her own safety as well as that of dad's. Is the agression/violence directed generally, or at one specific person? Are there any specific triggers?
If mum is so confused, her behavior so challenging, then the time may have come to consider residential care.