# A widebar equivalent for including a bar below letter

I was wondering if there is something that similar to a \widebar when I want to put the bar below a character. I am working in the math mode and here is the relevant preamnle

\documentclass[12pt,letterpaper]{article}
\usepackage[margin=1in]{geometry}
\usepackage[english]{babel}
\usepackage{amsmath}
\usepackage{xfrac}
\usepackage{nicefrac}
\usepackage{accents}
\newcommand\munderbar[1]{%
\underaccent{\bar}{#1}}

\newcommand*\widebar[1]{%
\begingroup
\def\mathaccent##1##2{%
\rel@kern{0.8}%
\overline{\rel@kern{-0.8}\macc@nucleus\rel@kern{0.2}}%
\rel@kern{-0.2}%
}%
\macc@depth\@ne
\let\math@bgroup\@empty \let\math@egroup\macc@set@skewchar
\mathsurround\z@ \frozen@everymath{\mathgroup\macc@group\relax}%
\macc@set@skewchar\relax
\let\mathaccentV\macc@nested@a
\macc@nested@a\relax111{#1}%
\endgroup
}


I am using the accent package to put the bar below the character of M_c.

Here is the line of codes I am using \munderbar{M}_{c} < M_{c}^{1} < M_{c}^{0} < \widebar{M_{c}}\$

I was wondering how make the bar below the last character, that is, M_c, wider like that of M_c with widebar appearing last.

The comment suggestion of \underline was rejected because of the size of the undergap in the presence of subscripts. Here, I offer \qunderline as an alternative. The stacking value of -1pt can be tuned to suit.

This 1st version only works in text and display styles.

\documentclass{article}
\usepackage{graphicx,amsmath,stackengine}
\newcommand\qunderline[1]{%
\ensurestackMath{\stackengine{-1pt}{#1}{\underline{\hphantom{#1}}}
{U}{c}{F}{F}{S}}%
}
\begin{document}
$M \underline{M_c} \text{\,vs\,} \qunderline{M_c} \qunderline{M_q} \qunderline{M_j^2}$
\end{document}


Here's a version that also works in smaller math styles:

\documentclass{article}
\usepackage{graphicx,amsmath,stackengine,scalerel}
\newcommand\qunderline[1]{\ThisStyle{%
\ensurestackMath{\stackengine{-1pt}{\SavedStyle#1}
{\SavedStyle\underline{\hphantom{#1}}}{U}{c}{F}{F}{S}}}%
}
\begin{document}
$M \underline{M_c} \text{\,vs\,} \qunderline{M_c} \qunderline{M_q} \qunderline{M_j^2} \scriptstyle\qunderline{M_j^2}$
\end{document}