I have a neighbor who has been hearing scratching noises in the walls and
ceiling.
They apparently got in through one or more broken vents
Her exterminator suggests two approaches
One is to set out poison. The downside is that the critters will die in the
walls and smell up the house.
The other is to set traps. The downside of this approach is the higher cost
of checking and rebaiting traps.

What is the best way overall of handling this problem?

Charlie