I have a 50,000.00 home mortgage at 5.9% interest fixed
And a variable rate home equity loan of 90,000.00 @2.5%
Should I concentrate on paying off the higher interest loan or the variable interest because it might go up at anytime?

I am assuming you will keep all of the payments up current and will want to pay extra toward paying one off.

Judgement call or guess, how much over the next 4 to 10 years will the variable go up ?

Short term I don't see it going up much for a few years.
I would put effort into paying off the current higher interest rate, and try to get it even paid off.
Then take all the money going toward it, to pay the other one off even faster.