Question

how did miss mebbin manage to get her weekend Cottage why did she plants so many tiger lilies in her Garden

Answer 1

Miss Mebbin managed to get the Weekend Cottage by Blackmail Loona.
She said that she will say the truth that Loona didn't shoot the tiger but the goat and the tiger died coz of heart failure. This made Loona tensed and she accepted the demand of Miss Mebbin as she need a weekend cottage. She planted tiger lillies as Tigers are the reasons why she got that cottage

Answer 2

Heya mate
The answer is here

♢ Miss Mebbin came to know that Mrs Packletide had arranged the tiger hunt just to prove herself better than Loona Bimberton.

☆☆ Therefore, Miss Mabbin blackmailed Mrs Packletide to get the weekend cottage to keep her mouth shut about knowing the fact that the tiger had not been killed by her actually and had died due to heart failure.

And , She has also planted tiger lilies in the garden because they were symbolic of how she had managed to get the cottage, that is due to a tiger...

hope it helps