She ain't just setting him up in a cosy cottage with a garden and care staff - she's giving him access to top secret UNIT history! He's getting all the dirt on the Doctor, Liz, Jo, Benton etc from the 70s/80s! He's getting to see all the alien artifacts collected over the years! Kate is going round there for tea and a chat every Sunday, sharing stories her dad used to tell her and updating him on what the Doctor is up to and Wilf's eyes are sparkling every time while trying not to cry because he can't have these chats with his granddaughter.
young kate stewart when her father brings home a guy who he exclusively calls 'the doctor' (claims he has no other name), spends half of his time arguing with, yet spends a solid three whole weeks mourning when he disappears each time, and spends most of his time with her telling stories about him: