The correct sentences are: 

この傘は雪子の傘です。(This umbrella is the umbrella of Yukiko / This umbrella is Yukiko's.)

これは雪子の傘です。(This is Yukiko's umbrella.)

You have to take care about the constructions of "this is ... " and "this ... is ~ ". 

I hope this helps you. 

does this make sense?

does this make sense? =
この傘は雪子の傘です。