If the coin was presented to her to honor her in some way, and cannot be replaced with insurance money, then yes, the government should offer her a new one if hers is not located. There are some things that money just cannot buy, and this is something that should be replaced, especially considering what she has gone through.
Betty Soskin has asked that her stolen coin be returned to her. It is very valuable because it was given to her by President Obama in a ceremony to mark her as the oldest park ranger. She claims she will forgive her attacker if the coin is returned. Until then, the White House will give her a replacement coin. Nowadays, she gives talks and tours at a historic park in California. This woman was honored for her years of dedication, and she should have her award with her for life. It makes perfect sense to give Betty a replacement coin.
The 94 old park ranger has a long service record and should be given new coin to replace the stolen one. The park ranger is the oldest full time ranger and deserves another honor for this special award. The park ranger was had a break into his apartment and was attacked so was not at fault.
If a person owns an item of value, they should seek out an insurance policy to protect the item from the event of theft or damage. If the park ranger valued the coin, she would have had it insured and the insurance company would have replaced it. It is not the government's job to do this.