Should I let mother-in-law go home?

If Mom can't understand why she can't care for herself, then there is skme cognitive decline.

It doesn’t sound like she’s competent to make decisions. Have you contacted her doctor about the changes in her attitude and behavior? She may need a med or change in meds that will help to calm her.

Sounds like she is in no condition to be alone.

Dscochrain, if she has ever been medically diagnosed by a physician with cognitive issues, I would certainly do everything in my power to keep her there. Even without that diagnosis she is displaying illogical, irrational thinking which should also tell you she needs to stay but I don't think you can legally keep her from leaving. It is no longer about what she wants (if it isn't in her best interest)...it's about what she needs. As her PoA this arrangement needs to work for the both of you. I manage care from here in MN for 2 very elderlies in FL. They are in their home. It is challenging now but full-blown stress is only a broken hip away. It would be so much easier to have them near me but I can't get that to happen quite yet. Does someone (like any relative) live near your mom if she goes back? If so maybe that person should be her PoA.

You don't give a time-line as to when her husband passed away and how long she has been in the care center. That info would be helpful. Also FYI if she does have some dementia, her asking to "go home" sometimes means her childhood home, as many on this forum will tell you. May you have peace in your heart over your decision.

If she’s still mentally competent, she has the right to make her own decisions no matter how bad they are. Your POA doesn’t give you control over her, it doesn’t allow to you stop her from going me unless she’s incompetent.

Poor MIL. So sad that she’s lost her caretaker/husband. He must have been a great guy to care for her with so many health issues.
She is grieving and missing her husband and her home. You sound sympathetic but now this.
You mention short term
memory issues. Does she remember her husband has passed? Does she realize how much help she needs?
Do you handle her finances?
The POA will have directions. Have you read it? Does it require a doctor or two to state that she is unable to make decisions before it becomes valid or is it one that gives you authority from the moment it’s signed? Is there anyone else to take this on, back where she lived?
Legally you may not have the right to stop her, but how would she manage it?
What many would do is take advantage of what is at hand. Tell her there is no travel allowed during the virus outbreak. Each person is to remain at home. Maybe not in your town but through the cities she would need to travel. Tell her there are no flights. Did she live in her own home or in IL? I’m assuming her own home. So it’s a big adjustment for her.
Do make sure she gets all the medical attention she needs. UTI check. Maybe her meds need adjusting. Is her diabetes controlled? That can make for a lot of irritable behavior if it is out of range. Who manages her shots? Takes her blood sugar?
Look up Teepa Snow on YouTube and watch how she deals with redirecting those with dementia. It’s really useful.
So my answer would be to stall regardless of her “rights”. Put her off. If she can’t understand about the virus it could be her short term memory is a little worse than you thought. We would all like to go back to a more manageable time. That’s sometimes what “going home” signifies.
Roads can be out, doctors are unwell, House needed repairs, car is in the shop, any reason that gets you away from the subject one more day.
Then start them all over as she will not have remembered.
She will adjust but she may need an antidepressant. She’s been through a lot. Stay Safe.