If a creature is affected by Supernatural Stamina and a Patron of the Vein is on the opponent's side of the field, does the creature come back after being destroyed or goes to Exile?
The wording on Patron of the Vein does not say "instead", but since its a treggered hability, it may resolve first.
Does the turn in whitch Supernatural Stamina whas casted matter for the stack order?
does the creature come back after being destroyed or goes to Exile?
It depends.
In this case, if the creature affected by Supernatural Stamina dies, two abilities trigger: Patron of the Vein's last ability and the ability granted to that creature by Supernatural Stamina. In this case, it does matter whose turn it is, since the two abilities are controlled by different players (C.R. 113.8) and so will go on the stack in active-player/non-active player order: starting with the one controlled by the active player or the player closest to the active player, and proceeding in turn order (C.R. 603.3b, 101.4). And the ability higher on the stack will get to resolve before the other (C.R. 117.4).
Thus, in general:
if the player controlling Patron of the Vein is the active player, the creature that died this way returns to the battlefield.
if the player controlling the creature that died this way is the active player, that card will be exiled and not return to the battlefield.
Note that in either case, when Patron of the Vein's last ability resolves, it will have Patron of the Vein's controller put a +1/+1 counter on each Vampire they control, since this action doesn't depend on whether something is exiled due to that ability (C.R. 101.3, 609.3, 109.5). See also this thread and this thread.
The wording on Patron of the Vein does not say "instead", but since its a treggered hability, it may resolve first.
Does the turn in whitch Supernatural Stamina whas casted matter for the stack order?
In this case, if the creature affected by Supernatural Stamina dies, two abilities trigger: Patron of the Vein's last ability and the ability granted to that creature by Supernatural Stamina. In this case, it does matter whose turn it is, since the two abilities are controlled by different players (C.R. 113.8) and so will go on the stack in active-player/non-active player order: starting with the one controlled by the active player or the player closest to the active player, and proceeding in turn order (C.R. 603.3b, 101.4). And the ability higher on the stack will get to resolve before the other (C.R. 117.4).
Thus, in general:
See also this thread.
Note that in either case, when Patron of the Vein's last ability resolves, it will have Patron of the Vein's controller put a +1/+1 counter on each Vampire they control, since this action doesn't depend on whether something is exiled due to that ability (C.R. 101.3, 609.3, 109.5). See also this thread and this thread.
Again, thank you.