We cannot locate the benef of an IRA. The account would have required a RMD before 12/31/13. If we do locate the benef after 12/31, will they be penalized for not taking the RMD? Any guidance is appreciated.

Any penalty that would be assessed for not taking an RMD (by the IRA owner or beneficiary) would be assessed by the IRS so it isn't much of your concern outside of any desire to provide customer service beyond what is required.

The answer though is, technically yes, if the RMD isn't taken by the IRA owner or their beneficiary before the year end deadline an excess accumulation penalty is owed by either the IRA owner or the beneficiary. It is very common for the IRS to forgive this penalty for beneficiaries when the facts and circumstances show a reasonable excuse for not taking the distribution by year end. If the IRA owner passed close to the end of the year and/or the beneficiary was unaware that they were even the beneficiary of an IRA they should be able to convince the IRS to waive the penalty. They would of course have to immediately withdraw the amount they should have taken as a show of good faith that they will comply with their distribution requirements going forward.