Which of the following order is wrong : -

First ionisation enthalpies (kJ/mol): Li 520, Be 899, B 801, C 1086.
Boron has a lower IE than beryllium because its outer electron is in a 2p orbital (higher energy, better shielded), whereas beryllium has a stable fully filled $2s^2$ configuration.
So the correct order is Li $\lt$ B $\lt$ Be $\lt$ C, and Li $\lt$ Be $\lt$ B $\lt$ C is wrong.
The other orders are correct: acidic character of hydrides increases down the group ($NH_3 \lt PH_3 \lt AsH_3$); basic character of oxides increases with metallic character ($Al_2O_3 \lt MgO \lt Na_2O \lt K_2O$); ionic radius increases down the group ($Li^+ \lt Na^+ \lt K^+ \lt Cs^+$).
So the wrong order is Li $\lt$ Be $\lt$ B $\lt$ C for first IP.