You totally did the right thing - I know it must be hard - but you have to protect the child first and foremost in any situation - they just can’t do it themselves.
I’m totally surprised at the response though - maybe not from the police if it’s not a massive safeguarding from their pov though usually procedure is to share with social care.
I have taken calls for social care before though as part of council calls, so not a specific triage person - we used to take details and children’s response team or a duty officer (depending when called in) would then triage but always, always follow up even if just a call to the relevant person. I’d never have commented on whether they could or couldn’t do anything as I wouldn’t know - just take the info and say they may/may not be in contact with you but it will be followed up.
As your dgs has preciously been on a protection plan and that will definitely have incorporated some rules around Mum’s ability to protect I’d be very surprised if they just didn’t/don’t bother.
I’m surprised the midwife /health visitor didn’t flag anything but maybe your daughter didn’t share her previous involvement with social care. Surprised at school s/g procedures too.
It sounds a huge mess but hopefully the MASH referral will set some support rolling for your dgs. Or actually if all these professionals have been looking into it and decided all is well then it mightn’t be as bad as you’re fearing - though I don’t really understand how that can be.
I don’t know what to say about your husband’s view - great he’s a kind man, but it seems to have gone far too far his policy of keeping everything sweet.
Your dgs will find you and he’ll know why you did this too - believe that will be ok - daughter may take longer - she’s clearly very troubled.
All the best.