These kinds of things can be tricky. The main issue is going to be action economy. 2 people are just never going to manage as much as 4 people. Being a higher level would help, certainly, but i think the bigger issue is that pregenned adventures assume a party with a variety of roles filled. I've gotten around this by using Gestalt rules so you can fill multiple roles with fewer people. If you don't want to do that (especially avoid if the players are new to the system), then I would advise looking into the various Hybrid classes (Investigator and Slayer are personal favorites). Bump them to 3rd level, and give it a go. adjust as needed from there.
The higher level will give them a bunch more health so they won't die as easy. Be careful with how much gold you give them, though, because a plethora of magic items will destroy anything designed to not have them involved yet.