To me, it looks about 30" wide.

I would be more inclined to go with 42"

I think you could do it, but it will depend on the size of the mirror and sconces. If the sconces are too large, then the mirror has to be too narrow to look right.

Here is a 36" vanity, according to the answers to questions on Houzz...looks like it could be if you count the subway tiles (assuming they are 6") on the backsplash.

[Contemporary Bathroom[(https://www.houzz.com/photos/contemporary-bathroom-ideas-phbr1-bp~t_712~s_2103) by San Francisco Interior Designers & Decorators Artistic Designs for Living, Tineke Triggs

This make up vanity is 34" wide...so picture a small sink. I like what they did with the mirror and sconces to make it look less crowded.

[Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Stamford Interior Designers & Decorators Tiffany Eastman Interiors, LLC

Yeah, I would guess greater than 40". Those handles are probably set 12 to 15 inches apart.