She needs to look at her tenancy agreement and see what it says about behaviour, not making noise at night, etc. What applies to her should apply to the other tenants, then make a formal complaint to the landlord. Make a note of the times, what happens, tape the noise if necessary. The fact that the neighbour is a friend of the landlord should not be relevant. The other thing she could do is speak to the other tenants - there is more power in numbers, if they all got together to petition the landlord.