What is the ruling on purifying the house and clothes from urine in the event of doubt about their impurity?

Water must be poured over the spot of urine until it is purified. Nothing else is required beyond that. If one is unsure whether urine has splashed onto something, the original presumption is that it has not. It appears that the questioner is afflicted with waswasah (whispers of Satan/obsessive thoughts), and it is advised to ignore them and not succumb to them, in order to avoid evil.