Was it best that Rose died?

[Eulaliaaa!]

Hmm, I disagree with that. Martin and his tribe lived in the cliffs for generations, Verdauga traveled to Mossflower while they were still living in the cliffs. They wouldn't have known about Verdauga and Mossflower.

[Jukka the Sling]

Actually, Luke's tribe was from Mossflower (Luke was born at St. Ninian's), but when Verdauga came and they were driven out, they headed to the cliffs.

[LT Sandpaw]

Luke's history is unknown so we have no idea if the cats drove them out, however I would like to think it was a long time before that. Martin would have been told stories of the wild cats that drove them from their original home, forcing them to live in the caves.
In LoL Luke does mention Saint N in and old rhyme, so we have to assume that they had been wandering for some time after they left the church for whatever reason, probably not due to the Wild Cats.

Hmm, I disagree with that. Martin and his tribe lived in the cliffs for generations

Remember Martin was the first mouse born under the cliffs so they hadn't been living there long. 

[James Gryphon]

Unfortunately I don't have Legend of Luke handy to make educated comments about this, but this is at variance with what the Redwall wiki notes about Luke's tribe and history:

The tribe of Luke the Warrior was a group of mice who originally resided at Saint Ninian's Church in Mossflower Woods until Verdauga Greeneyes drove them out sometime during the early stages of his rule. Luke the Warrior himself was born at Saint Ninian's.

[Eulaliaaa!]

Oh, my bad. I haven't read Legend of Luke in a while. Here:

"Old Ninian mouse and his goodwife,
Needed a house to build,
They had a family grown so large,
Their tent was overfilled.

To setting sun the old wife toiled,
From daybreak in the east,
But Ninian was a lazy mouse,
Who loved to sleep and feast.

The wife heaved stone and carried wood,
For door and wall and beam,
While Ninian idly in daylight,
Snored on in peaceful dream.

She raised the gables, built a roof,
Her back was bent and sore,
As Ninian ate up all the food,
And loudly called for more.

So when the house at last was built,
His wife nailed up a sign,
Which stated, 'THIS AINT NINIANS!'
She said, 'That shows 'tis mine!'

Then when countless seasons passed,
And all within had died,
The rain and storm of ages long
Had swept the sign outside.

It washed the first three letters out,
But left the rest intact.
That sign now reads, 'S AINT NINIANS!'
A church? A joke? A fact!

So traveler if you read this sign,
Then take my word 'tis true:
A dreamer can become a saint,
So can a glutton too!"

Welff applauded with the rest, chuckling and shaking her ad at Windred's song.
   "Tell me, Windred m'dear, is it true, is there such a place as Saint Ninian's, or is it really a joke?"
   Luke answered for her, " 'Tis a fact, marm. I was born at Saint Ninian's, as was Sayna my poor dear wife. We were drive out, when I was a babe, by an evil warlord, a wildcat named Lord Greeneye Verdauga who had a horde of vermin at his command, so they told me, but I was far too young to remember. This is our home now, and nobeast will ever drive us from here while I am about."
-Legend of Luke, page 171-173.
Hope that helps, I didn't remember that until I found it in the book.