Is the issue that she is an alcoholic or that she is a thief?
If you just care that she is a thief, stop leaving her alone in your house.
If you care that she's an alcoholic, maybe give her friend the heads up so maybe she can talk to her? Telling her she needs help isn't going to come off as anything other than an attack if it's coming from the person whose booze she drank. Let one who can relate with her situation try to help.