If their children can not help them with their expenses, then a reverse mortgage help them. They would receive monthly payments until both of them pass away. The property would then either be sold, and the remaining amount go to their heirs, or their heirs can payoff whatever the balance of the mortgage was at the time.
Some children of the elderly object to this because they feel like they are going to "get" less, but this is not about them - it is about their parents not being able to survive on their meager retirement income.
I personally have not done one of these loans, but I think it is a great way for seniors who are cash-poor, but home equity rich to increase their income without worrying about paying it back.