export default function () {
  return [
  {
    "id": "1",
    "title": "car",
    "items": [
        {
          "id": "01",
          "name": "Mazda"
        }, {
          "id": "02",
          "name": "Honda"
        }, {
          "id": "03",
          "name": "Maruti"
        }
    ]
  },
  {
    "id": "2",
    "title": "Bikes",
    "items": [
        {
          "id": "01",
          "name": "Ducatti"
        }, {
          "id": "02",
          "name": "Harley Davidson"
        }
    ]
  }
];
}

export default function () {
  return [
  {
    "id": "1",
    "title": "car",
    "items": [
        {
          "id": "01",
          "name": "Mazda"
        }, {
          "id": "02",
          "name": "Honda"
        }, {
          "id": "03",
          "name": "Maruti"
        }
    ]
  },
  {
    "id": "2",
    "title": "Bikes",
    "items": [
        {
          "id": "01",
          "name": "Ducatti"
        }, {
          "id": "02",
          "name": "Harley Davidson"
        }
    ]
  },
  {
    "id": "3",
    "title": "Scooters",
    "items": [
        {
          "id": "01",
          "name": "Bajaj"
        }, {
          "id": "02",
          "name": "Scooty"
        }, {
          "id": "02",
          "name": "Sunny"
        }
    ]
  }
];
}

Update stuffReducer.js