In regard to inheritance and vesting of real property, there is no statute of limitation per se. At the time she passed away, the property vested (subject to claims of creditors) in the devisees of her will or her heirs at law if she had no will. Unless she was married and the property passed to her surviving spouse via tenancy by the entirety or unless there were joint owners that had survivorship interests in the deed, there should have been some evaluation as to whether probate administration was needed at her death. I would advise you consult a probate lawyer in your area that also handles real estate matters so you can determine what ownership interest you have in the property.
LEGAL DISCLAIMER-An attorney can only give you competent legal advice if he or she knows all the facts and is licensed to practice law in the state specific to your question. The comments above are not intended to be legal advice but general comments based on the limited information provided in the question. I am only licensed to practice in the State of Tennessee.
Assuming there was no will, you can file an Affidavit of Heirship as to ownership of the real property. There is no deadline for doing so. However, if you are concerned that the "older person" may be at risk of financial exploitation, then you should consider other steps to protect that person, such as having an attorney in fact appointed and the name added to bank accounts (as POA only, not as joint owner) and having copies of bank statements sent to the POA or so the POA can gain on-line access to bank account transactions. If the "older person" refuses to appoint an attorney in fact, and is unable to manage her own financial affairs, consider talking to an attorney about possibly creating a conservatorship. This step would be a last resort, but is sometimes necessary to protect elders.