What do you do with/in a will when ...?

In the end there's not enough funds left to disburse as directed. For example my grandma's will says: $3000 to each of her 3 granddaughters, $1000 to her best friend, $1000 to a specified children's charity and the remainder, including material goods, to my mom. It was updated last in 1997, my grandma is now ill, and we were just wondering what you do if she passes and we find only like $5000 left in her savings. Just curious, none of us are concerned nor want her money, but I just wondered what you do in that case.