All she needs is a series of notes that sound like the chord happening at that moment (arpeggio!). This is one way to think of it:
There are 3 basic types of chords, Major (happy), Minor (sad), and 7th (happy but in a bluesy way, or functioning to lead to the next chord)
Each chord has 2 names:
1)Alphabetical (A-G plus the #'s and b's)
2)Quality (major, minor, 7th)
All she needs to be able to do to get started on bass is to be able to match any quality with any alphabetical letter name (therefore creating a sequence of notes that sound like the chord).
These shapes have there "root" on the 4th string (the root note gives the alphabetical name) so whatever letter name you put the "R" in the pattern will be the alphabetical name and the geometric pattern you play will provide the quality.
Major =
-|-|-|-|-|
-|-|-|-|-|
-|o|-|-|o|
-|-|R|-|-|
Minor =
-|-|-|-|-|
-|-|-|-|-|
-|-|-|o|-|
-|R|-|-|o|
7th =
-|-|-|-|-|
-|-|o|-|-|
-|o|-|-|o|
-|-|R|-|-|
Here are the notes of the 4th string:
Open E|F| |G| |A| |B|C| |D| |E .........................................or by the fret numbers 0|1| |3| |5| |7|8| |10| |12|
Here is the same thing for patterns rooted on the 3rd string:
Major =
-|-|-|-|-|
-|o|-|-|o|
-|-|R|-|-|
-|-|-|-|-|
Minor =
-|-|-|-|-|
-|-|-|o|-|
-|R|-|-|o|
-|-|-|-|-|
7th =
-|-|o|-|-|
-|o|-|-|o|
-|-|R|-|-|
-|-|-|-|-|
Here are the notes of the 3rd string
Open A| |B|C| |D| |E|F| |G| |A .........................................or by the fret numbers 0| | 2|3| |5| |7|8| |10| |12|
These 6 shapes (3 per string on the E and A strings) are a great starting point for being able to play a short sequence of notes that "sound" like a chord. For example if you needed to sound like a G minor chord, you could find the note G on the 4th string (which lives at the 3rd fret) and that would be your "R" (Root note or starting point, the note that gives the chord its alphabetical name). Then you would choose the geometric pattern that will give you the quality "minor" which would be the second pattern above.
This is of course a very simplified way of looking at what a bass line really is, but I think it could be a great place to start working from. Its good too because there are only a few shapes to remember and 2 strings worth of letter names, and it provides a very complete chord vocabulary.
Here is a theoretical progression, just for example:
|C major |A minor |D minor |G 7th |
You could use the major pattern with R on the 3rd fret of the 3rd string for C major
You could use the minor pattern with R on the 5rd fret of the 4th string for A minor
You could use the minor pattern with R on the 5rd fret of the 3rd string for D minor
You could use the 7th pattern with R on the 3rd fret of the 4th string for G 7th
Anyway, just thought I would see if I could put this concept into words and hopefully it was in some way useful for you. Also, I am assuming that your UBASS is tuned EADG, if not I can edit it for whatever tuning you have. Thanks!