This week, we have seen Elly unable to talk in candid terms about death. She required the euphemism "dust to dust" while discussing the disposition of cremains, and then became upset when her father used the flippant euphemism "pop off" for the act of dying. Here, we see April all upset that John would make a joke about death. While April does finally turn around and make a joke about spending her inheritance, we see that the seeds of Junior Jellyism have taken root. It took Liz awhile to develop into a fully Jellytonian adult woman as well. This strip is meant to show us that we shouldn't fear--even Martian April will turn out right in the end.
By the way, April--you shouldn't be counting on an inheritance. First, your mother tends to forget you exist, and you can guarantee she'll be the one deciding who gets what when the wills are drawn up. Second, your father doesn't approve of you wanting to go into a musical profession, so you can bet that if you do get money, your parents will attach plenty of strings. Third, your parents value marriage and family above all. Until you are married and have kids, you will be less deserving in their minds. If they die and you don't have a husband and kids, you can bet the lion's share will go to Mike's brood, and probably Liz's too. Without offspring, you'll likely end up out in the cold with the Frenchy step-granddaughter. Keep that in mind.