Nor you, ye proud, impute to these the fault, If Mem'ry o'er their tomb no trophies raise, Where thro' the long-drawn aisle and fretted vault The pealing anthem swells the note of praise.
The speaker has more advice to proud, rich, hoity-toity people: He addresses them as "ye proud," and tells them not to blame ("impute […] the fault") these dead poor dead people if they don't have fancy monuments ("trophies") over their graves.
More personification! Again, it's like the speaker is displacing blame. He says that "Memory" failed to put up fancy trophies or monuments, but really, wouldn't that be the responsibility of the families of the dead people? But of course, the dead guys in the churchyard are mostly poor farmers, so obviously their families wouldn't be able to afford a fancy marble monument in the church itself. So, the speaker shifts the blame onto the personified "Memory."
The last two lines of the stanza describe the church itself—the place where the monuments might be displayed.
The bell that marks the passing of a member of the church "peals" in praise of his or her life all through the aisles of the church and up to its high, arched ("vaulted"), ornamentally carved ("fretted") ceiling.