If you are in a hurry, you should take MRT to Tiong Bahru and
take bus 195 from the bus stop opp Tiong Bahru Plaza.
If you have a lot of time, there are many ways to get from Bedok to
Depot Rd.
(1) Take 25 or 854 to Jalan Eunos (after PIE flyover), cross the
road and take 5 to Kim Seng Rd (Great World City), and change to
175/195
(2) Take 30 to Harbourfront and change to 57
(3) Take 7 to North Bridge Rd and change to 175
(4) Take 32 to North Bridge Rd (City Hall MRT) and change to
195
(5) Take 33 to Tiong Bahru and change to 195
etc etc