Money help: My story starts 4 months ago when my dad showed up at my door with money that he needed to store away for safe keeping. - Help.com

Have you called the police? This is a serious problem. The person who stole his money from your sister could have been the same one who stole the money from you as well.
For it to happen twice, I’m thinking it’s the same person.

Bad news doesn’t get better with age. You should have called the police, pronto. By the way, it isn’t smart to store money in your house. Safes get ripped out of walls and out of floors, and carted away. Tell your father. Also, tell the police. Be prepared to tell them who could have possibly known about the safe. I don’t think anyone will be sending you money, unless it’s Bill Gates. All of you have, unfortunately, just learned a $20,000 lesson.

Here’s a possible “solution.” Call various insurance companies that offer life insurance for older persons. My mother, who is 85, recently took out one for $10,000 for around $90 per month. Perhaps you can get one for $20,000 for around $200 per month. Make SURE that the policy you get has rates that do NOT go up as your father gets older, or coverage that goes down. Then you will have ensured that he will have a proper and decent funeral when that time comes. Eventually, however, he’s going to want to check on the safe. Now, are you doggone sure he didn’t come and get it himself? Again, call the police before the trail grows any colder. And never, ever store large sums of money in a home again!

I suggest you start saving your money to pay back your father. It was your responcibility, you lost it now you pay it back. Hope this helps :-)