If the holder of the life estate is that far gone in her ability to care for herself, it sounds like it may be appropriate to involve community mental health in her care. Depending upon the full facts and circumstances they may decide that she should be placed under a guardianship and relocated to a location where she can get a suitable level of care and attention. Also, given that this appears to have been an official notice from the city, it sounds like the house may be in danger of losing its certificate of occupancy - if that happens the occupant will not be able to live there until the home is repaired and recertified for occupancy. You can potentially make a claim for waste against the occupant, although the odds are such a claim would only be good as leverage for trying to get the person to surrender the life estate as it does not sound like this person has money.

You can bring an action to eject her for waste, but consider the above when determining your options. I would suggest discussing your options with a local real estate lawyer. Ejectment is probably going to be your most expensive option, which is why I am suggesting you consider alternatives which may unfold under these facts.