“Neighborhood children, I mean. We thought the washing machine was eating the neighborhood children.” It’s a possessed washing machine, so that statement isn’t as weird as it sounds.
Maybe the owner is only talking about the missing socks. In that case, yes, sometimes the washing machine does “eat” socks. (Fun fact: If you’re missing some socks, check under the agitator. Sometimes they’ll slip under there during the wash cycle) However, if Marm was taking the socks, why are they all sitting in front of his dog house? Is that where they’ve been the whole time? If so, why did the owner just now notice them? Why would Marmaduke even want socks? Honestly, it’s easier to believe the comic is about Marmaduke eating people. At least it matches previously established continuity.
For his part, Marmaduke has an expression that conveys “Oops, you caught me eating people again. I’m sowwy.” We all know that this isn’t going to stop Marm from eating anyone. The only change that might occur is the owner family will sleep extra close to their shotguns tonight… they know that eventually Marmaduke is going to turn on them. It’s just a matter of when.
Final verdict: I think it might be a little bit safer if we all sleep extra close to our shotguns tonight.