Corrected entry: How did the Lycans know the exact location of the safe-house that Michael was in? Selene told Michael that they take the Lycans there and remove the silver bullets in order to question them. After questioning they put the bullets back in. Since the vampires would put the silver bullets back into a Lycans body the lycan would eventually die and therefore it would be impossible for any knowledge of the safe-house or any others to be discovered.
Tailkinker
6th Jul 2004
Underworld (2003)
Correction: Given that Kraven is in league with the Lycans, it's not remotely out of the question that he might have revealed the location of the safe house at some point.
Correction: The lycans that eventually nab Michael are shown in an earlier scene watching Selene drive onto the mansion grounds through night vision binoculars. It's not unreasonable to assume they waited for her to leave again and followed her.