The best time for hiking in most of Myanmar is November to early March. It’s not too much rain and the temperature is not so hot. 
Between your 3 options:
– Kyaukme:  Variable difficulty, day tour : yes

• Beautiful walking in north-eastern Myanmar around the pleasing town of Hsipaw, accessible from Mandalay.  Lovely tea plantation trek in (relatively) nearby Nanshan.

• You can visit intact tribal villages in their irrigated fields. Visit monasteries and waterfalls

• There is a wide range of day walks to choose from, and you can make overnighters, too. Guides are a good idea.

– Kalaw: Variable difficulty, day tour : yes

• Fine trekking around forested hills and farmed valleys. You can also enjoy the abstract harmonies of tea plantations.

• Treks vary from half day to multi day and can be organized locally.  An overnight expedition, sleeping in a tribal village, would be a must, if time allows. 
• Some way off is Pindaya, home to a famous Buddhist cave.  There is lovely walking around the town, with pagodas on nearby high points and trekking out to tribal villages in the surrounding area.  These can be day treks, or overnighters.
• Beautiful Inle lake has some good walks in its environs. 

– Kentung:

• Spectacular and exciting walking in the formerly lurid and dangerous Golden Triangle area of far eastern Myanmar.

• Rough mountains nestle remote and intact tribal villages in their irrigated fields. You can move between several ethnic groups in a day’s walk.

• There is a wide range of day walks to choose from. Guides are a good idea