The beneficiary on any property is the actual mortgage holder. When a residential property such as a residential single-family house ends up in foreclosure due to borrower's failure to keep up with repayment obligations, it is sold at public auction according to the local foreclosure laws.
When no third party bidder makes a bid at or above reserve price set by the mortgage holder, the unsold property reverts back to the beneficiary, who is also the mortgage holder.
If the status is indicated as "sold to the foreclosing beneficiary," it basically means that the house no longer belongs to the defaulting home owner. It's now owned by the bank or mortgage lender who initiated the foreclosure proceedings.