After all the sadness and awful of the previous two comics, I figured that poor Alphys deserved one that was more of a happy ending! So, the Amalgams get to go home.
Except dogs rely on their nose and not their eyes, remember?
That, and monsters have a tendency to look on the bright side. Also, if they're happy to see their family members again...well, works for them, works for me.
...And also, as stated in-game, at least Lesser Dog has a brain the size of a piece of kibble.