If you have a concern about someone you should never ignore it. 

If it is possible to gather some evidence safely - without placing yourself at risk or compromising any potential police investigation - then do so. It will strengthen any referral you may want to make to adult safeguarding/protection. If it is possible to speak to the person concerned (but not to whoever you suspect of being the abuser) then do so if you feel they will be able to talk to you safely.

In other circumstances, then report your concerns to the adult safeguarding/protection team at the council/local authority, as they will be able to make contact and check on the person that you are concerned about.  Reporting abuse to the adult safeguarding/protection team can be done anonymously, and you have a right to maintain your anonymity if you wish.

It is important to understand that an older person experiencing abuse may not positively respond to your approaches, or that of statutory agencies, as the situation may be challenging, embarrassing or distressing to them - particularly if the potential abuser is a member of their family. They may feel a range of emotions, including denial, helplessness, embarrassment, guilt and very often fear of the perpetrator. It can often take various attempts for the victim to acknowledge their circumstances and engage in accepting support.

Offering the older person emotional support and providing small steps for them to build their confidence might be a vital part of them making a bigger change, and dealing with the situation.