Awww TB, I'm sorry. That caregiver stress tests just how heavy a load you can carry. Know that you're not alone.
There are always things to deal with and once you do, a few more pop up to take their place. It seems never ending.
Does your mil get meals on wheels? If not, you might want to look into it. Would help in several ways. What looks to be a delicious meal would be delivered every day. She'd have contact with someone outside of family, someone is checking on her daily, and it's one less meal for you to worry about for her.
That was so nice of you guys to take her supper and groceries. She must have enjoyed that so much. Does she do any crafts, or computer things?
Have you considered grocery store online ordering and pickup, or delivery to help you limit your public contact? There are grocery stores and pharmacy's that can save you a world of stress and keep you safer. That's my main method now. Keeping the receipt is good for a good guesstimate of when someone is going to be needing another purchase. Like you, I'm not supposed to be out and about. Stayed home all winter, now it's become all summer. LOL.
How are your kidneys doing? Are you under a Dr. care right now? Feeling ok?....or as ok as can be expected.
It has to be a real burden to miss the grands. Makes you really think about long ago when people had multiple family homes. It's easy to think how that must have lightened many loads.
You're a real rainbow in your mil's world. Hope you see some in your own life real soon. Truly do with I could help you. Virtual hug is the best I can offer.