Smileless, it was MIL gran who was involved in the fallout with the mum. The mum had plenty of rows with her own mum mind, and some shockers with the aunty (her sister). But it was MIL who carried the can in the end, the other gran has always passionately detested her amd strongly encouraged the NC.
(I have known this MIL since I myself was very small and she has always been very kind to me, I am very fond of her. Both she and the little one have really struggled with the drastic change in their relationship and it is still a sore point several years later. Yes, she has her eye rolling moments like everyone does, but frankly I would swap her for mine in a heartbeat)
But to return to the topic: if there is a possibility of this kind of awful outcome in a family, nursery might be better. Sometimes it’s not wise to go looking for trouble when there is already plenty.
I don’t know where OP goes from this point. Where is the husband/son in all of this? Is there anything he has or is willing to do to defuse tensions and try to get everyone on the same page? The weekly visits must be less than pleasant for everyone involved with things being as they are.
How old is baby, did I miss this? Under nine months or so if EBF?