Buy some earplugs and suck it up. Its a couple of hours for goodness sakes.
If for some reason DH no longer has any interest, he can always sell the tickets
This. Just go and people watch, take a break to walk around, go buy a t-shirt. It will be over before you know it.
Or, you could tell your MIL that she is more than welcomed to buy the tickets but she must be the one to go with him!