Trying to build a relationship with someone who just lost a parent is NOT optimal timing.
Since you were friends first, I would suggest you tell her you care & that you would like to give her time to grieve. That you don't want to add any pressure on her to do with your relationship at this time. Emphasize the caring part and that you are NOT breaking up with her, just giving her the space she needs by supporting her as a friend.
Leave the ball in her court. She will love you for this if you have something good. Only an asshole would pressure a girl (or guy) when they are going thru a loss like that.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh