Hi holidayobsessed,
Diwali is celebrated all across India, so you'll get to experience it wherever you go. The celebrations in smaller towns like Bundi will probably be more traditional, compared to the more commercial displays in larger cities like Jaipur (we were there around Diwali in 2018).
That being said, the only true way to celebrate Diwali is with a family of locals, because it's a very personal thing. But since you're probably staying in a homestay in Bundi, that'll be taken care of.
In case you're interested in some insight into things in an around Bundi, we visited in November last year. Here's a blog post: https://thegoodlifewithiq.com/2019/02/18/bundi-gem-off-beaten-track/