When a 95-year-old woman died in a fire in her apartment on the East Side yesterday morning, the police said that she had most likely dropped her cigarette while sleeping. But some neighbors were not surprised -- they had long noticed that the elderly woman on the 10th floor was too frail to be left alone safely but too stubborn to accept more supervision. Tenants in the co-op building noticed cigarette burns on her dress. They held their noses when she repeatedly left food burning in the kitchen. They held meetings to discuss the problem, which seemed to get worse as the years fell away. And in the end, their fears were realized in a swirl of smoke and flames.