@Devlesko
All those saying she's a stranger well the nursery staff aren't even related to the child, certainly don't love their charges, and of course were actual strangers at the beginning.
Trust them at nursery you should trust a mil who has raised the son you married
My DC went to nursery.
They weren't at all related to the carers, or knew them, which was why they had settling in sessions, and were obviously pretty unsettled and upset at first.
When they got used to going, got to know the carers, and understood that nursery was a place they went without mummy or daddy - all good.
We also lived a long way from family, so when they were very little they really didn't know grandparents well. Yes - they were related. Big deal, to a baby/toddler it's a person they don't know!
If I'd decided to just leave mine for the day at home, where they were used to being with mummy/daddy, in the care of any of the grandparents, just like that, they'd have found it really upsetting and unsettling. They would probably have spent most of the day anxiously looking for me/DH (because home is where we care for them) and would have been quite frightened to be honest.
Not exactly great bonding time. Can folk really not see that?
Honestly, if you want MIL to have a pleasant time getting to know her grandchild, leaving her in sole care at home after the child not seeing her for a long time, for the whole day, would be the absolute last thing I'd do. One of mine at least would probably have had the horrors if the grandparent had come anywhere near them after that!