It's worth considering that a slightly overbearing MIL or DM for that matter might be a bit of a godsend if things don't go to plan 
I was in labour for 2 days, then EMCS, and in hospital for another 4 days before discharge [in the UK]. Baby was early so we were not set up at all at home. Visiting hours were v restrictive so DH could only come for short durations and I was getting sod all sleep in the hospital.
Mil [who can be a bit of a pita on occasion, but nobody is perfect and don't get me started on my own] who I generally get on quite well with; got the nursery sorted with DH, waited in for deliveries, shopped, cleaned out the fridge, did all the batch cooking I'd planned to do on my non-existent pre birth mat leave, and delivered home cooked lunches and dinners to the hospital so I didn't have to survive on the utterly dire hospital food.
We'd had to call her while I was still in labour as the cot/pram etc were due to be delivered and there was no-one at home to meet the delivery. So she was at the hospital at 4am when I was eventually wheeled away to surgery, and she stayed with our DD while DH ran back and forth between recovery where I was, and the room that DD was in. I think she stayed another 48 hrs after I was discharged and then left us to it. All DH wanted to do was hold DD when I wasn't feeding her, so again she bustled around and generally made our lives easier at a time when I could barely climb the stairs.
My own parents came to visit from overseas for a week a few weeks later and expected to be waited on hand and foot...... they couldn't be more different!
She's also fond of turning up and gifting us unwanted furniture that she can't seem to bring herself to ditch. Could murder her for that
If you spend enough time on MN though, you'll probably consider yourself blessed in the MIL department soon enough.
I think asking her to pick up your mum is a cracking idea. Both of them will probably be arriving with a ton of baby stuff that you'll have to be tactful about 
Best of luck !!