The band admired by Miss Garnet's pupils is of course, The Grateful Dead.
But Miss Garnet's book refers to a common theme in folk tales: the dead doing favours for the living in return for decent burial. The example below is from a 1908 collection by G.H. Gerould, the American folklorist:
A German count (presumably an impoverished one) heard that a beautiful, rich young woman had offered to marry the winner of a jousting contest. He travelled to the place where the tournament was to be held, and managed to find lodgings and a horse, but both came with conditions. The landlord of the lodgings demanded that he pay off the debt of a dead man, whose corpse had been left to rot in a dung heap. Feeling sorry for the dead man, the count paid the ransom and arranged a decent burial, which took nearly all of his money, so that he then had to borrow from his landlord. He obtained a horse from a strange knight, on condition that, if successful in the joust, he 'share his winnings'. The count, being generous, but perhaps also rash, agreed; he might have done well to consider carefully the meaning of the agreement. He won the tournament and married the girl, but the honeymoon was disrupted on the second night by the strange knight's bursting into the bridal chamber and demanding to replace the bridegroom in the marital bed. The count was in despair. Luckily, however, the intruder turned out not to be a love-rival after all, but only the ghost of the dead man, who obligingly disappeared.
The ghost showed his gratitude by providing the horse and not taking up the count's foolish offer to share the reward. (How grateful was he really, though, I wonder? Would he still have provided the horse if the count hadn't agreed to the conditions? And how useful was the reward to him, anyway? Wouldn't a ghost need a substantial supply of Viagra to take advantage of a bride?)