Argentine playmaker Carrusca and central defender McKain, both out of contract at the end of the season, are considering the deals presented to them by the Coopers Stadium outfit.
The Reds head coach is particularly keen to keep hold of Estudiantes academy product Carrusca, but knows there is no guarantee he will commit his future to the club.
"We bring an offer to him. Now he is thinking and in the next days need to (give) us an answer," Gombau said.
"The club sends him an offer and it's what the club can afford. Now it's time (for him) to decide if he wants to stay with us or he has another offer and wants to leave. We want (him) to stay because he is an important player for us. If not, then it's the moment to start to look for other players.
"You keep the same players, it's better for everybody. All the work we did this year, the players know. You start to change players, it will be more difficult. Because the new players that come need to adapt to the style, need to know everything.
"I like not to change a lot but sometimes decisions don't come from the club. The club can bring an offer to the player. The club have a quantity of money which we can spend ... the players want to stay, we are happy. If the players of course have another options that's better in terms of money for them, wants to leave - (in) that moment we need to find another player."
An impressive run of form has seen Adelaide climb to fifth on the table, seven points behind second-placed Western Sydney Wanderers.
Speaking ahead of Friday's match at home to reigning champions Central Coast, who are just three points ahead of his team in third spot, Gombau did not dismiss the Reds' chances of sealing a top-two finish.
"I want to go game by game," he said.
"Then we will see where we are. We want to work hard and of course every single game play the best that we can to try to win the games. And if, at the end, we are top two, it's perfect. If we get (in) the finals, it's also very good."
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