Mom is 87, my siblings and I are all adults, our kids are all adults. Mom goes into a state where she insists she has to go home and cook for the kids. I know it is not useful to say you don't have any little kids. What is something compassionate to say? I've tried, Mom I know how much you care for the kids but everyone is safe and wants you to relax.
In the end, you may find that medication to take the edge off these delusions is a good way to go. A geriatric psychiatrist can help.
Mom took Seroquel to help with the windowing issues and worry about those little girls was frequent. She started Seroquel with 12.5 my daily at 4:30 that gradually increased to 75 mg over the course of 3.5 years.
I must watch what my autocorrect does much closer!
"Betty, Susan and Brian" called and said they are having lunch (or dinner) at Cathy's house then they are going to go to a movie. (or study) and they will be home later.
or
The kids went shopping for a few things when they get back they want to surprise you and make dinner.
or
The kids are at school right now, we have plenty of time to get dinner ready. Why don't we go for a walk now.
Anything that you can say to help change the subject, deflect the situation is fine.
Its so hard to say the right thing that won't upset them. Sometimes you just have to go along with them. Maybe just say "Mom you know the kids have made other plans for dinner tonight. Thats why you are having dinner here" Then pray that she forgets what you said so u can use it again.