She was unable to walk so certainly not in her senses. But that also I doubt how can she get so drunk that she can’t walk , did he give something to her
So hammered. Maybe she legit does not recall and that is where witnesses other than yourself are important.
did he give something to her
Tox screening at the time might have been able to tell but as time passes so do chemicals. If it was Rohypnol she would not have been able to respond to you. Rohypnol will stay in the system for 72 hours. Be very sensitive if she is your friend and you plan to talk to her about this. Hopefully someone trust-worthy gave her a ride home.
Should I tell her your manager was hitting on you ?
Hitting on someone is heavy flirting. Flirting does not involve touching, especially if that person is your subordinate. Either way that is a power conflict. Just tell her what you told us, just the facts. If she wants your help then find out if anyone else witnessed what happened.
To clarify this is if she is your friend. If just a colleague then just talk to HR and let them sort it out.