It will depend on how much additional care mum requires as to which option you are better off with as yu may not qualify for carers (there is an allowance and a payment -you may as well apply for both)

As to the dollars you should run the estimator. There may not be a big difference in the maximum payments for each but the way your partners (or yours if you do any work) is treated is different. If you go on the website, select o line estimators, and then compare centrelink rates you will be able to get an idea of your entitlements.

I THINK carers is the better option BUT I don't work in that payment area so not sure. The estimator is your best bet