begin{table}[h]
centering
    begin{tabular}{ | p{1.2cm} | p{1.6cm} | p{1.6cm} | p{1.6cm} | p{1.6cm} |}
    hline
    multirow{2}{*}{Scenario} & multicolumn{2}{|c|}{Urban} & multicolumn{2}{|c|}{Highway} \
     & Without RSU & With RSU & Without RSU & With RSU \ hline
    PDR & e-HBCWC & HBCWC & e-HBCWC & \ hline
    End-to-End Delay & e-HBCWC & DCF & HBCWC & \ hline
    Overall & e-HBCWC & e-HBCWC & e-HBCWC & \ hline
    end{tabular}
end{table}

documentclass{article}
usepackage{booktabs}
begin{document}
begin{table}[htp]
centering
addtolength{tabcolsep}{-2pt} % adjust to fit
begin{tabular}{lllll}
toprule
 & multicolumn{2}{c}{Urban} & multicolumn{2}{c}{Highway} \
cmidrule(lr){2-3}cmidrule(lr){4-5}
Scenario         & Without RSU & With RSU & Without RSU & With RSU \
midrule
PDR              & e-HBCWC     & HBCWC    & e-HBCWC     & \
End-to-End Delay & e-HBCWC     & DCF      & HBCWC       & \
Overall          & e-HBCWC     & e-HBCWC  & e-HBCWC     & \
bottomrule
end{tabular}
end{table}
end{document}

documentclass{article}
usepackage{multirow}
newlength{without}
newcommand{adjustsize}[1]{makebox[without]{#1}}
begin{document}

begin{table}[!htb]
settowidth{without}{Without RSU}
addtolength{tabcolsep}{-2pt} % adjust to fit
begin{tabular}{ | *{5}{l|} }
hline
multirow{2}{*}{Scenario} & multicolumn{2}{c|}{Urban} & multicolumn{2}{c|}{Highway} \
& Without RSU & adjustsize{With RSU} & Without RSU & adjustsize{With RSU} \ hline
    PDR & e-HBCWC & HBCWC & e-HBCWC & \ hline
    begin{tabular}{@{}l@{}}End-to-End\ Delayend{tabular}
      & e-HBCWC & DCF & HBCWC & \ hline
    Overall & e-HBCWC & e-HBCWC & e-HBCWC & \ hline
end{tabular}
end{table}

end{document}