I don't think that Real Sociedad's third place gives it the status of some special opponent, especially considering that the game will be at the Santiago Bernabeu. Even Atlético, which is traditionally considered a serious opponent for Real and Barcelona, has been beaten by both clubs this season. It seems to me that Real Madrid will not have problems with Sociedad. But by the way, Barcelona's away game can bring a surprise.
I may go all in for both clubs straight winning over the weekend and stake a good amount on the, I am sure that both Everton and Real Madrid will win in their various match slated for the weekend, most especially now that their facing a lesser evil sociedad as a club doesn't have what it take to give it opponent a tough fight so the match will be seamlessly won. Judging also from the odds provided by bookmakers you will see that both clubs are given smaller odds and that is a pointer to what to expect in the match. 
Everton? Do you think Evertno will win their next (I even had to check their schedule after reading your post - I thought maybe they have some kind of cup game against a obviously weaker side) match against Arsenal? 
In general, I do not advise anyone to go all-in, in this case, even more so. I think you mixed up something or I misunderstood you.