How did Rat realize Mole's pain and help him search his house?

In chapter V, Rat helps Mole to search for his house, and once inside, to search for food. Mole and Rat are out walking together when Mole catches the scent of his old home nearby and implores Rat to help him find it. At first, Rat is worried that it is about to snow and also does not see the point; he keeps walking and urging Mole to catch up. When they sit down to rest and Mole starts to cry, Rat realizes he is deeply troubled. Mole bursts out,

"I know it's a—shabby, dingy little place," he sobbed forth at last, brokenly: "not like—your cosy quarters—or Toad's beautiful hall—or Badger's great house—but it was my own little home—and I was fond of it—and I went away and forgot all about it—and then I smelt it suddenly—on the road, when I called and you wouldn't listen, Rat—and everything came back to me with a rush—and I wanted it!—O dear, O dear!"

Recognizing that he has been “a pig—a plain pig,” for ignoring his friend’s wishes, Rat decides they will go look for his home: “I'm going to find this place now, if I stay out all night.” Relying on Mole’s nose, they find it down a tunnel, and Rat dives after Mole. There it is, with the name intact:

Rat saw that they were standing in an open space, neatly swept and sanded underfoot, and directly facing them was Mole's little front door, with "Mole End" painted, in Gothic lettering, over the bell-pull at the side.

Once inside, Rat bustles about and admires everything. When they want to make supper, he encourages Mole to look for some canned fish and then pronounces their concoction a banquet.

Why, only just now I saw a sardine-opener on the kitchen dresser, quite distinctly; and everybody knows that means there are sardines about somewhere in the neighbourhood. Rouse yourself! pull yourself together, and come with me and forage.

They went and foraged accordingly, hunting through every cupboard and turning out every drawer. The result was not so very depressing after all, though of course it might have been better: a tin of sardines; a box of captain's biscuits, nearly full; and a German sausage encased in silver paper.

"There's a banquet for you!" observed the Rat, as he arranged the table. "I know some animals who would give their ears to be sitting down to supper with us to-night!"

The ultimate coup, though, is successfully turning up some beer: Rat “made for the cellar-door, and presently reappeared, somewhat dusty, with a bottle of beer in each paw and another under each arm.”