@Jennifer1774 Make sure there are no toxic cleaning products anywhere in the unit that a child could get to. Even up on a counter isn't safe- an active 2 year old can climb on a chair and up onto a counter in a moment when a parent's back is turned. Most parents of a 2 year old will travel with what is needed for the child- toys, child dishes, travel cot, etc. unless they are staying somewhere that normally caters to families with children. It sounds like this guest is clear that you don't normally host children, so shouldn't be expecting you to provide a lot of stuff just for their booking. Hopefully they also have a waterproof pad that they use for changing diapers, if the child still wears them, if not, maybe you have something around that would work. And I certainly hope you have a waterproof mattress protector on the bed!
You might also give them a pile of clean, but threadbare or stained towels that they could use for accidents and clean-ups, that could just go into the garbage if necessary afterwards.
Little people come with as diverse characters as the adults they grow into. Some are loud, rambunctious and and need to be constantly watched. Others are quiet and calm and you'd barely know they were there but for the fact that they need to be fed and dressed and bathed.
I got my kids used to showers from a very early age, even though we had a bathtub, simply because I'd seen too many kids have absolute freak-outs when first having to take a shower, even at the age of 5 or 6, if all they were used to was a bath.