I'm really sorry but I must take umbridge with your comment about why didn't she just look after him.
I work with older adults, sometimes the ONLY option is a nursing home. To keep them safe, to keep their relatives safe. Very few people (some do want to be cared for, different strokes for different folks ofc) choose to go or put their family member in a cared for facility. There simply isn't always the option to keep them at home.
If Greedy's nan is able to still live at home and look after herself with or without care and other help, then there must have been some monumental reasons for him leaving the house and living in a cared for facility.
I say this only because when I talk to family members about this at work, the amount of guilt and shame a lot of them feel is massive. Sometimes it's just not do-able safely. Care at home only goes so far, so if someone needs supervision constantly and assistance with all their daily tasks, it's not going to be enough. It's not an easy option in any circumstance and it really grates on me that people assume that you can 'prevent' people going into a home. They exist for a reason; to keep people safe and well when they cannot be kept safe and well in their own homes with their own family.