What do I do if my landlady won't evict the tenants committing domestic violence?

I am disabled and have PTSD from domestic violence. When I moved in I was assured it was very peaceful and quiet here. This is a small four-plex. It was very peaceful and quiet until this couple moved in. He is an alcoholic who also uses medical marijuana (I don't care about the latter - I do too) and they fight a lot. Lately the fights have been louder and more violent, to the point that the police had to come a few nights ago. He successfully fled the police that night though they had police everywhere looking for him. They stayed for a few hours and then left. The tenant came sneaking back late that night. They often have loud drinking parties and have visitors who steal things from the common areas (like the laundry room and parking stalls). I have observed their visitors going through our garbage, talking to themselves, and obviously hallucinating. I am home almost all of the time because I am very ill and this is stating to affect my health detrimentally. My landlady is aware of the situation but at 95 is finding it hard to be firm with these tenants. What should I do? I do not have the option of moving at this time.