This sounds like too much coincidence.
Sure, panic and paranoia can easily justify why the inn owner is being accused of having the disease but it still doesn't add up, the disease is known but it is clearly being controlled, she and the other settlers are practically isolated from most people and to reach them it is needed to pass by the main village so on that note if she and the other had it that village is as good as dead too, but the soldiers are going directly to her.
I can think of two options: It is jealousy because she was granted amenities with taxes... but still, it would be too much for some other village to cause all this because of that, more so with the many details pertaining to investigation and veracity; The other reason, it is the spice her and her husband discovered, which is the most likely reason, as spices were always a commodity that gave a lot of money for those trade it, but there is still the fact that she isnt the owner of the spice she is just a cook the feudal lord is the one that would have ownership of its trade.
There are still missing pieces here, this first try from Bard may not end well as these soldiers have already too much in mind and are resolved because of their grim task.