What should I get my 4 yr old niece?

Ask her parents.  A parent ALWAYS knows with their child needs.

boxes of cupcake mixes, biscuit mixes, cheesecake mixes, cake mixes. rotary hand whisk. silecone bun trays.Hours of fun making  goodies with help.

A four-year-old would have the dexterity to sew. Not as in real Needles and Pins and threads and patterns, but there are crafts that use yarn and plastic needles to sew things together. I think everyone should learn how to sew.

There are plenty of crafts that include sewing. Sewng is a skill that every single person I know needs at one time or another.

There is an amazing game out called Violated Heroine, and if that is not her kind of thing then I would reccomend Teaching Feeling.

you have already answered your own question.

A tablet so she can draw on it.

Get her a arts and crafts set . It has art pens and paints and stuff like that . It can be abit costly if you look at the wrong place 

A pacifier ---------------------------

Craft supplies or craft kits, maybe paints and throw in a set of building blocks. 

How about some painting sets, arts and crafts, building blocks ?