tobie, ciebie, ty. Dla tobie, dla ciebie, dla ty. o tobie o ciebie, o ty.
these are different cases of the pronoun ty (you, singular, familiar, like Spanish, French Italian tu, German du)
tobie - date case 'to you' 'for you',
ciebie - accusative and genetive (you, your)
ty - nominative case (you, by itself or as the subject of a sentence)
Dla tobie - mistake no such form exists
dla ciebie - for you
dla ty - mistake, no such form exists
o tobie - locative case (about you)
o ciebie - for/about you preposition o 'about' and ciebie 'accusative of ty'
o ty - vocative 'oh you...' (should be followed by a noun in the vocative case