The illness makes it harder, especially if they are emotionally manipulative, it gives them a lot of ammunition.
I suggest getting your husband to agree that parenting discussions and decisions should be between the two of you. No one else. They get to be grandparents and enjoy that experience, but everyone needs to stay in their lane here. You're not cutting them out as grandparents, you're just insisting that parenting decisions are made by the parents and no one else. As they should be!
Then you have a clear rule to fall back on. When they are sticking their nose in- ask him 'is this a parenting issue?'
Childcare = Parenting issue and none of their business (NOTB)
Your return to work =Parenting issue & NOTB
Where child goes to school = Parenting issue & NOTB
Likewise
Whether child would like a ride on toy as a present for Christmas = Grandparent issue
Cute photo or story you would like to share = Grandparents welcome
Shall we all go to the zoo = Grandparents welcome.
I have had the same issue with my DH. He just deferred to his parents in everything and then would come to me and present their opinions as his own. Eventually I cracked it and said I will not be Parenting via committee. They have raised their family, they are done. They don't get a vote in how we raise ours.
He pushed back, argued his parents wishes should be considered. What stopped that argument was when I said 'ok then, if your parents get a vote- how about mine do as well? Oh and my siblings have some thoughts I am sure. Where shall we draw the line? Should I ring up my second cousins and ask them to weigh in too?'
Bowing to his parents was natural to him but he was bloody horrified at the idea of having to take orders from my parents. Which I helpfully pointed out what exactly what he was expecting me to do for his parents time and time again without complaint.
Stand your ground. No on childcare from family. You aren't comfortable with it for a number of incredibly valid reasons.
MIL does not get to hold the family hostage for the duration of her illness. Absolutely be supportive and compassionate and generous to PIL, but not at the expense of your own family unit, independence or peace of mind.
Your DH is a dick for refusing counselling. What reason did he give for this? Your feelings don't matter enough for him to spend one hour feeling uncomfortable? How many uncomfortable hours have you spent with his family for him?