I'd be wary of committing to this. On your own, in bad weather or dark evenings it could be no joke.
I'll be 67 in July and have found over the last year or two that my eyesight for driving and my stamina have reduced considerably.
I know we're all different, but if you find the first few months ok and then struggle increasingly to keep it going, that could be more difficult than just saying no to start with.
Offering to help pay for a childminder would probably cost you less than the fuel, wear and tear on the car, and reduction in pension.
You could offer to go some Friday/Saturdays when you're off, stay over and let your daughter ( & partner?) have a night out and/or help with specific tasks. You could make that a fairly regular thing.
On the other hand, if you feel fit and able, don't mind driving in snow or in the dark, wouldn't mind if it extended to two children..... and were thinking of retiring anyway - it might suit you to do this.
The fact you are asking GNs suggests you are unsure of committing to this. You don't want to end up doing it but being really stressed/tired and not wanting to let your daughter down so carrying on to your detriment.
I assume your working hours/days couldn't be amended to facilitate this without retiring?
All the best whatever you decide.