The best way to reach Munnar is by road as there is a good connectivity of buses from all major cities of Kerala. There nearest Airport and railway station is more than 100Km away. Also while in Munnar the best way is to travel by state run/private buses only if you are trying to save some bucks, otherwise you can hire a cab as well. You can look for best accommodation in Munnar using this link https://www.tripoto.com/hotels
myself and my friends (all girls) travelled to munnar a month and half ago. we stayed at Nandanam homestay at Devikulam which is 9 km from Munnar. the best way to reach is travelling to aluva railway station or Ernakulam station and take a bus frome there. its about Rs 120 and buses are available one for 2 hours and the last bus is at 5pm in the evening. The Homestay is very very safe and there lives a lady who is very friendly. she looks hot meals and the total room For This 1500 per 24hours. they even arrange transport for you if you want . we all felt like home there for 4 days. you can check my post regarding that. hope you have good time !