Personally i'd put George V pretty high on my list of "successful" monarchs - his arch conservatism was probably the one thing that helped ensure that the British Monarchy survived the aftermath of the first world war and the social upheaval of the twenties - i won't go into the issue around asylum for Nicholas II and his immediate family as its been discussed elsewhere although he had sound reasons for it. As to the rest of the family - Xenia received financial support and a home from George V, George VI and Elizabeth II until her death and she remained on good and friendly terms with George V, Queen Mary and Princess Victoria until their deaths, George V also paid a not insignificant pension to the Dowager Empress until her death - to be fair George V in financial terms did more than any of their other royal relations and Xenia and her mother were included in British Royal occassions throughout the twenties. Xenia was still attending and being invited to events into the 1950's.
It is worth bearing in mind that the only surviving Romanov's closely related to George V were Grand Duchess George (Greek Minny - 1st cousin - born Princess Marie of Greece), Grand Duchess Xenia Alexandrovna (1st Cousin), the Empress Dowager (aunt) and Grand Duchess Olga Alexandrovna (1st cousin).