B2 Visa purpose of visit, which is good option

[mvrs]

We want to apply visa for my Mother-in-law(widowed). She has 2 kids(including my wife). Both are in USA.
We have 2 options
1. Me sponsoring her
2. She sponsoring herself for her son's Graduation Ceremony. He is graduating in May.

Is it easy to get a visitor visa if the purpose of visit is Graduation Ceremony?

Thanks in advance for the time.

[jnk]

Option 2.