Make sure to get a bus back from Kausani to Haldwani leaves at 2 p.m. then you have to hire private taxis to Haldwani, or you can also a direct bus leaving at 11 a.m. from a village called 'Garud' which between Kausani and Baijnath(This bus should leave you around 3 in night at Anand Vihar Bus Station).
Quick questions that would be helpful:
1. When to Visit:
Depends on you, though September till December are times of cold weather, so carry light woolens. If you can handle, September to October can be done in full sleeve shirts.
2. How much:
Typically you can do a this trip in Rs.2000-3000, this can go up according to the comfort level.
3. For Whom:
a. Singles: Solo, Peace Lovers, Untouched places, Budget Trippers
b. Couples: Secluded time, Honeymooners
4. Avoid If:
a. You're looking for more famous places like Shimla, Manali, Mussoorie etc
b. Looking for some adventure
c. Looking for commercial Touches
5. How to Plan
Considering you have a weeekend to spend,
Get a late night bus/train from delhi till Haldwani/Kathgodam> Reach Mid-day/Late Morning>Sightseeing>Return to haldwani at nearly 6p.m. on sunday>Get bus to Delhi and reach late night/early morning around 3-4 a.m.(Depending on time taken)
This can be changed as per suitability.