So, an ex-MIL. She had invited her grandchildren to spend the half term at her house. The father of the children, her son, voluntarily has limited contact and lives overseas. Ex-MIL is retired and running a B&B in her house in a remote area which does not seem to be a financial success and is rarely booked. But the house itself is nice and the area is quite picturesque, but not touristic. It will be the first time she will see one of the children, and she hasn't seen the older DC since they were a baby (both are young primary age).
Now it turns out that the father made other plans for the half term and cannot spend it with the children anymore. So the ex-MIL had sent an email to the mother of the children confirming that they are still welcome to visit her as she appreciates that making alternative holiday plans at such a short notice may be difficult, but she now would expect them to pay for the accommodation at her B&B. "Mates rates", but still in excess of £100 / day.
AIBU to think this is a "fuck off and don't even think of turning up here"?