Diana, to get a better idea of when she arrived in Australia, and to find the ship, have you looked at her 1856 marriage record? In case not, I had a look at the Vic bmd Search facility, and there was only one marriage recorded in 1856 of Thomas William Vicary to Bridson. I didn't put in her forenames at first because they give "no result" at the slightest variation.

I then tried her names, and she appears to have been entered as "Eliza" - but as there is only one entry anyway, I'd leave it blank.
online.justice.vic.gov.au/bdm/index-search

There were several Eliza Bridsons in passenger indexes pre-1857, so if you have already looked at her marriage cert., do you know roughly when she arrived? What was her bapt date?

Sue