What can be done to help a senior citizen who lives alone-no relatives close by?

Depression can do a number on people. Especially if husband handled the finances. I go with Ahmijoy.

I would suggest calling Adult Protective Services in your area:
at 1-877-597-2331

You can call Adult Protective Services and report a Senior Citizen at risk, but they will not investigate whether or not the housekeeper is scamming her. You would have to have solid proof that her funds are winding up in the housekeeper’s pockets and without access to her finances, there is no way you can prove this. APS will not be able to do anything unless they see signs of abuse or neglect. Without Power of Attorney, you cannot gain access to her financial records. If she has told you that the housekeeper is stealing from her, keep in mind that a good percentage of people with dementia claim they're being stolen from. Arrangements may have been made between the daughter and the housekeeper for the housekeeper to have financial responsibilities for the mother. But again, without proof and POA, there is t much, if anything, you can do.

If it were me, I would contact her daughter. As next of kin, even if her relationship with her mother is not good, she does have a responsibility to her mother and may even have POA. That way, you will have done “something”. You will have notified the daughter of your suspicions and it’s up to the daughter to take it from there.