\documentclass[a4paper,12pt]{memoir}
\usepackage{etoolbox}
\makeatletter
\@ifpackageloaded{tex4ht}{
\usepackage[utf8]{inputenc}
\usepackage{devng4ht}
}{%
\usepackage{fontspec}
\usepackage{xltxtra}
\setmainfont[Script=Devanagari]{Sanskrit 2003}
\usepackage{polyglossia}
}

\usepackage{fontspec}
\usepackage{longtable}
\usepackage[landscape,margin=1.5cm]{geometry}
\RequireXeTeX
%English
\newfontfamily{\en}[Script=Latin]{FreeSerif}
\setmainfont[Script=Latin]{FreeSerif}
%sanskrit
\newfontfamily{\sk}[Script=Devanagari,
UprightFeatures={Language=Sanskrit},
BoldFeatures={Language=Sanskrit},
]{FreeSerif}
%oldhindi
\newfontfamily{\oh}[Script=Devanagari,Language=Default,
	UprightFeatures={RawFeature={+hlig},Ligatures=Historic},
BoldFeatures={Ligatures=Historic},
]{FreeSerif}
%hindi/marathi
\newfontfamily{\hi}[Script=Devanagari,Language=Default]{FreeSerif}
%bombay styleset
\newfontfamily{\bby}[
UprightFeatures={Script=Devanagari,Language=Default,StylisticSet={02}},
BoldFeatures={Script=Devanagari,Language=Default,StylisticSet=2}
]{FreeSerif}
%calcutta styleset
\newfontfamily{\clt}[
UprightFeatures={Script=Devanagari,Language=Default,StylisticSet=3},
BoldFeatures={Script=Devanagari,Language=Default,StylisticSet=3}
]{FreeSerif}
%nepali styleset
\newfontfamily{\npl}[
UprightFeatures={Script=Devanagari,Language=Default,StylisticSet=4},
BoldFeatures={Script=Devanagari,Language=Default,StylisticSet=4}
]{FreeSerif}
%Other Unicode Devanagari Fonts
\newfontfamily{\sItrans}[RawFeature={Conjuncts=Additional Conjuncts}]{Sanskrit 2003}
\newfontfamily{\sNagari}[Script=Devanagari,Language=Default]{e-Nagari OT}
\newfontfamily{\sSIL}[Script=Devanagari,Language=Default]{Annapurna SIL}
\newfontfamily{\sSahadeva}[Script=Devanagari,Language=Default]{Sahadeva}
\newfontfamily{\sNakula}[Script=Devanagari,Language=Default]{Nakula}
\newfontfamily{\sChandas}[Script=Devanagari,Language=Default]{Chandas}
\newfontfamily{\sUttara}[Script=Devanagari,Language=Default]{Uttara}
\newfontfamily{\sSid}[Script=Devanagari,Language=Default]{Siddhanta}
\newfontfamily{\sMangal}[Script=Devanagari,Language=Default]{Mangal}
%%
\newcommand{\tstdeva}[2]{{#1} & \sSahadeva{#2} & \sUttara{#2}  & \clt{ #2} &  \bby {#2} & \sk{#2} & \sItrans{#2} & \sNagari{#2} & \sSIL{#2} & \sChandas{#2}  & \sNakula{#2}   & \sMangal{#2}\\}

\begin{document}
  
\pagestyle{ruled}
\begin{longtable}{|l|c|c|c|c|c|c|c|c|c|c|c|c|c|c|c|c|}
\caption[FreeSerif Devanagari]{Unicode Devanagari Fonts - Ligatures Test  } \label{styles_deva} \\
\hline Sample Text & \en{Sahadeva}  & \en{Uttara} & \en{Calcutta } &   \en{Bombay}  & \en{Sanskrit}  & \en{Skt2003}  & \en{eNagari}  & \en{S I L} & \en{Chandas}    & \en{Nakula}  & \en{Mangal} \\ \hline 
\endfirsthead
\multicolumn{17}{c}%
{{\bfseries \tablename\ \thetable{} -- cont.}} \\
\hline & \en{Sahadeva}  & \en{Uttara}  & \en{Calcutta }  & \en{Bombay} & \en{Sanskrit}   & \en{Skt2003}  & \en{eNagari}  & \en{ SIL}  & \en{Chandas}   & \en{Nakula}  & \en{Mangal}\\ \hline 
\endhead
\hline 
\endfoot
\hline \hline
\endlastfoot
\hline

\hline
\tstdeva{ r-voc}{ऋ} 
\tstdeva{ rr-voc}{ॠ }
\tstdeva{ l-voc}{ऌ}
\tstdeva{ ll-voc}{ॡ}
\hline
\tstdeva{Incorrect Usage}{}
\hline
\tstdeva{r halant r-voc}{\char"0930\char"094D\char"090B}
\tstdeva{h halant  r-voc}{\char"0939\char"094D\char"090B}
\hline
\tstdeva{Correct Usage}{}
\hline
\tstdeva{ra r-voc maatraa}{\char"0930\char"0943}
\tstdeva{ha  r-voc maatraa}{\char"0939\char"0943}
\hline

\end{longtable}
\end{document}
