so which rule would over ride the other? would the player still be able to get their card back or does dryad militiant exile it before?
{Dryad Militant} would win and exile the card. {Tamiyo the Moon Sage}'s emblem requires the card to hit the graveyard first before it returns to the hand, but the militant's replacement effect stops the card from ever reaching the graveyard in the first place - straight to exile.
With dryad or {rest in peace} in play, cards (or in this case instants and scorceries) aren't sent to the graveyard, they are simply sent to exile. So tamy emblem means squat.
Tangent note:
I was playing 3 player edh and the red/white player goes turn 2 RIP GB graveyard deck goes scoop. I continue to play and turn 5 red/white player scoops due to only having 3 land. Best game ever.
/tangent
Sounds rather boring lol
Wait, so if I enchanted them with {Wheel of Sun and Moon} and have a dryad what happens?
Depends who controls the wheel, not who it enchants.
If the same person controls both the wheel and the dryad they use whichever replacement effect they want (if a choice applies, like an instant or sorcery resolving).
If not, assuming the active player controls one of them, the one they control happens. If the active player controls neither, the first person in turn-order who controls one of them will affect the card.
If this isn't how it works, then timestamps take precedence (as in, the most recent one to enter the battlefield will affect instants and sorceries).