elderly rent control tenant can no longer look after herself

Have an 82 year old rent control tenant who is no longer able to care for herself.  Falls frequently and can no longer operate a phone.  No relatives in the country.  Legally I can't 'harass' her into leaving but I'm concerned I may also have liability for not doing anything since she should be in assisted living, etc.  Anyone know an expert or someone who has dealt with this situation before?  It must come up fairly often now with the rent control population demographics.  Thanks.