Question: Why does Lori tell Daryl that Rick will show him where his brother is but then 10 minutes later tried to talk Rick out of going?
Answer: It's not shown, but I think Lori is suffering from some sort of PTSD due to thinking her husband had died, having an affair with Shane and of course the zombie apocalypse as well! This isn't the only time she contradicts herself so it kinda backs this theory up.
Answer: No, she actually tries to talk Rick out of it, but he's already made up his mind, minutes later when Daryl asks him about the location of his brother Lori says "he'll show you."